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Research

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Common Generic Names

Electrolytically Generated Hypochlorous Acid (HOCl)
Neutral Electrolyzed Water (NEW)
Electrolyzed Oxidizing Water (EOW)
Electro-chemically Activated Water (ECA)
Super-oxidized water (SOW)

Results: 341 published articles

Microbe(s): Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

Electrolyzed water (EW) is known by its bactericidal efficacy and capability to oxidize organic matter. The present research evaluated the efficacy of recently developed electrolytic cells able to generate higher concentration of reactive oxygen species using lower power and salt concentration than conventional cells. This study tested the inactivation of Escherichia coli O157:H7, the organic matter depletion and trihalomethane (THM) generation by EW in process wash water under dynamic conditions. To achieve this, clean tap water was continuously added up to 60 min with artificial process water with high chemical oxygen demand (COD) inoculated with E. coli O157:H7, in experiments performed in a pilot plant that recirculated water through one electrolytic cell. Plate counts of E. coli O157:H7, COD, THMs, free, combined and total chlorine, pH, temperature and oxidation-reduction potential were determined. Results indicate that the novel electrolysis system combined with minimal addition of NaCl (0.05) was able to suppress E. coli O157:H7 population build-up and decreased the COD accumulation in the process wash water. THM levels in the water were relatively high but its concentration in the washed product was marginal. Highly effective electrolysis has been proven to reduce the occurrence of foodborne diseases associated to cross-contamination in produce washers without having an accumulation of THMs in the washed product.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

ABSTRACT – Full Text PDF

This paper focused on the effectiveness of electrolyzed water (EW) at different concentrations (5, 25, 50 and 100 mg/L) combined with passive atmosphere packaging on the quality of mushroom. In order to understand the effect of EW on mushrooms, gas composition inside packages, weight loss, pH, whiteness and browning index, texture profile analysis (TPA), cap development, electrolyte leakage and FT-NIR analysis were performed during the twelve days of storage at 4 C. Samples washed with 25 and 50 mg/L EW consumed O2 lower than the other treatments. Mushrooms treated with 25 mg/L EW had a significantly lower electrolyte leakage values than untreated and 5 mg/L treated mushrooms. Mushrooms treated with 25 mg/L EW had the highest whiteness index and lowest browning index. EW treatments at the concentrations of 25 and 50 mg/L maintained the textural parameters and slowed down the weight loss better than other treatments. FT-NIR analysis supported the results obtained by weight loss and electrolyte leakage. In conclusion, the results of this research support the idea that combined of EW treatment and passive modified atmosphere packaging can be used to extend the shelf life of mushrooms.

Microbe(s): Microbe(s): Colletotrichum fructicola

ABSTRACT – Full Text PDF

Neutral electrolyzed water (NEW: pH 6.57.5) applied through an overhead irrigation system was evaluated for control of strawberry anthracnose caused by Colletotrichum fructicola. Conidia of the pathogen were completely killed by a 10-s exposure to 10.0 mg/L of available chlorine in the NEW. Disease suppression was significantly higher using the NEW treatment through overhead irrigation, either alone or combined with fungicides, than using conventional fungicides. Plants had no visible phytotoxicity after the NEW treatment, even when combined with fungicides. Thus, the NEW treatment was effective at controlling anthracnose caused by C. fructicola.

Microbe(s): Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

In order to evaluate slightly acidic electrolyzed water (SAEW) and sodium hypochlorite solution, the washing agents on shelf-life and quality were investigated during 25 days cold storage. The resultsshowed that the specific maximum peak force of lettuce and carrot significantly increased after treated with SAEW, while carrot with sodium hypochlorite solution treatment was not significantly (P > 0.05) increased. Also the shelf-life of lettuce processed with SAEW was prolonged for another 4.5 days. The results indicated that SAEW technology had stronger decontamination ability than sodium hypochlorite with its conveniences.

Microbe(s): Listeria monocytogenes, Salmonella enterica

ABSTRACT – Full Text PDF

The goal of this study was to enhance the antimicrobial effect of slightly acidic electrolyzed water (SAEW) through addition of synergistic treatment with ultrasound (US) and mild heat treatment in order to improve the microbial safety of fresh-cut bell pepper. To evaluate the synergistic effects, the Weibull model was used to mathematically measure the effectiveness of the individual and combined treatments against Listeria monocytogenes and Salmonella Typhimurium on the pepper. The combined treatment (SAEWUS60 C) resulted in the TR values of 0.04 and 0.09 min for L. monocytogenes and S. Typhimurium, respectively, as consequence of the minimum value. Subsequently, texture analysis was carried out to test the potential effect on quality of the samples due to the involved mild heat and ultrasound treatment. When compared to the control, there was no significant change (p 0.05) in the texture (color and hardness) of the samples that were treated by 1 min of the combined treatment (SAEWUS60 C) during storage at 4 C for 7 days. This combined treatment achieved approximately 3.0 log CFU/g reduction in the two pathogens. The results demonstrate that the involved hurdle factors which are ultrasound and mild heat achieved the synergistic effect of SAEW against the two pathogens. According to the results of texture analysis, 1 min of SAEWUS60 C is the optimal condition due to without negative influence on the quality of the samples during the storage. The optimal condition shows the enhanced antimicrobial effect of SAEW and enables to improve microbial safety of fresh bell pepper in food industry as a consequence of hurdle approach.

Microbe(s): Microbe(s): Multiple

ABSTRACT – Full Text PDF

Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidation-reduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of 800 to 900 mV. Vegetative cells of various bacteria in suspension were generally reduced by >6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.

Microbe(s): Propionibacterium acnes, Corynebacterium, Staphylococcus aureus, Staphylococcus epidermidis

ABSTRACT – Full Text PDF

Purpose To examine the magnitude of bacterial reduction on the surface of the periocular skin 20 minutes after application of a saline hygiene solution containing 0.01 pure hypochlorous acid (HOCl). Methods Microbiological specimens were collected immediately prior to applying the hygiene solution and again 20 minutes later. Total microbial colonies were counted and each unique colony morphology was processed to identify the bacterial species and to determine the susceptibility profile to 15 out altering the diversity of bacterial species remaining on the skin under the lower eyelid.

Microbe(s):  Total Microbial Count

ABSTRACT – Full Text PDF

Objectives/Hypothesis We aimed to evaluate the effectiveness of low-concentration hypochlorous acid (HOCl) nasal irrigation compared to isotonic normal saline for pediatric chronic rhinosinusitis. Study Design This was a randomized, prospective, active-controlled study.MethodsThis study investigated the effectiveness of 4 weeks of low-concentration hypochlorous irrigation by analyzing five categorized subjective symptoms and x-ray findings in pediatric patients with rhinosinusitis. Thirty-seven patients were enrolled, and 26 patients successfully completed the study. Results Total symptom scores significantly improved with both HOCl and normal saline nasal irrigation, but there was no difference between the two groups. X-ray scores also improved in both groups improvement was much greater in the HOCl group than the placebo group. Conclusions Nasal irrigation with HOCl is an effective adjuvant treatment compared to isotonic normal saline for pediatric sinusitis.

Microbe(s):  Escherichia coli, Porphyromonas gingivalis, Enterococcus faecalis, Streptococcus sanguinis

ABSTRACT – Full Text PDF

Chemotherapeutic agents have been used as an adjunct to mechanical debridement for peri-implantitis treatment. The present in vitro study evaluated and compared the effectiveness of hypochlorous acid (HOCl), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) at eliminating Gram-negative (E. coli and P. gingivalis) and Gram-positive (E. faecalis and S. sanguinis) bacteria. The effect of irrigating volume and exposure time on the antimicrobial efficacy of HOCl was evaluated, and a durability analysis was completed. Live/dead staining, morphology observation, alamarBlue assay, and lipopolysacLPS) detection were examined on grit-blasted and biofilm-contaminated titanium alloy discs after treatment with the three chemotherapeutic agents. The results indicated that HOCl exhibited better antibacterial efficacy with increasing irrigating volumes. HOCl achieved greater antibacterial efficacy as treatment time was increased. A decrease in antimicrobial effectiveness was observed when HOCl was unsealed and left in contact with the air. All the irrigants showed antibacterial activity and killed the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants. Moreover, HOCl significantly lowered the LPS concentration of P. gingivalis when compared with NaOCl and CHX. Thus, a HOCl antiseptic may be effective for cleaning biofilm-contaminated implant surfaces.

Microbe(s):  Enterococcus faecalis

ABSTRACT – Full Text PDF

Introduction This study evaluated the bactericidal effect of strong acid electrolyzed water (SAEW) against flow Enterococcus faecalis biofilm and its potential application as a root canal irrigant. Methods Flow E. faecalis biofilms were generated under a constant shear flow in a microfluidic system. For comparison, static E. faecalis biofilms were generated under a static condition on coverslip surfaces. Both the flow and static E. faecalis biofilms were treated with SAEW. Sodium hypochlorite (NaOCl, 5.25) and normal saline (0.9) were included as the controls. Bacterial reductions were evaluated using confocal laser scanning microscopy and the cell count method. Morphological changes of bacterial cells were observed using scanning electron microscopy. Results The confocal laser scanning microscopic and cell count results showed that SAEW had a bactericidal effect similar to that of 5.25 NaOCl against both the flow and static E. faecalis biofilms. The scanning electron microscopic results showed that smooth, consecutive, and bright bacteria surfaces became rough, shrunken, and even lysed after treated with SAEW, similar to those in the NaOCl group. Conclusions SAEW had an effective bactericidal effect against both the flow and static E. faecalis biofilms, and it might be qualified as a root canal irrigant for effective root canal disinfection.

Microbe(s): Enterococcus faecalis

ABSTRACT – Full Text PDF

Objective: The purpose of this study was to determine the antimicrobial efficacy of sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in human root canals infected by Enterococcus faecalis. Study design: One hundred sixty-five human single-rooted teeth were prepared and inoculated with E. faecalis for 48 h. Teeth were divided into 3 experimental groups according to the irrigation pattern used: group 1, 4.2% NaOCl pH 12; group 2, 4.2% NaOCl pH 7.5; and group 3, 4.2% NaOCl pH 6.5. Samples from the root canals were collected, and bacterial growth was analyzed by turbidity of the culture medium. Results: None of the irrigating solutions used in this study demonstrated 100% effectiveness against E. faecalis. The antibacterial effectiveness of 4.2% NaOCl at pH 6.5 was significantly increased (P = .03) compared with 4.2% NaOCl at pH 12 (chi-squared test: P < .05). Conclusion: Bactericidal activity of NaOCl solution is enhanced by weak acidification of 4.2% NaOCl solution at pH 6.5.

Microbe(s): Viruses, Norovirus

ABSTRACT – Full Text PDF

Noroviruses (NVs) are the most frequent cause of outbreaks of gastroenteritis in common settings, with surface-mediated transfer via contact with fecally contaminated surfaces implicated in exposure. NVs are environmentally stable and persistent and have a low infectious dose. Several disinfectants have been evaluated for efficacy to control viruses on surfaces, but the toxicity and potential damage to treated materials limits their applicability. Sterilox hypochlorous acid (HOCl) solution (HAS) has shown broad-spectrum antimicrobial activity while being suitable for general use. The objectives of this study were to evaluate the efficacy of HAS to reduce NV both in aqueous suspensions and on inanimate carriers. HOCl was further tested as a fog to decontaminate large spaces. HOCl effectiveness was evaluated using nonculturable human NV measured by reverse transcriptase PCR (RT-PCR) and two surrogate viruses, coliphage MS2 and murine NV, that were detected by both infectivity and RT-PCR. Exposing virus-contaminated carriers of ceramic tile (porous) and stainless steel (nonporous) to 20 to 200 ppm of HOCl solution resulted in 99.9% ( 3 log10) reductions of both infectivity and RNA titers of tested viruses within 10 min of exposure time. HOCl fogged in a confined space reduced the infectivity and RNA titers of NV, murine NV, and MS2 on these carriers by at least 99.9% (3 log10), regardless of carrier location and orientation. We conclude that HOCl solution as a liquid or fog is likely to be effective in disinfecting common settings to reduce NV exposures and thereby control virus spread via fomites.

Microbe(s):  Staphylococcus epidermidis

ABSTRACT – Full Text PDF

The purpose of this study was to investigate the mechanism by which a direct electrical current reduced the viability of Staphylococcus epidermidis biofilms in conjunction with ciprofloxacin at physiologic saline conditions meant to approximate those in an infected artificial joint. Biofilms grown in CDC biofilm reactors were exposed to current for 24 hours in 1/10th strength tryptic soy broth containing 9 g/L total NaCl. Dose-dependent log reductions up to 6.7 log10 CFU/cm2 were observed with the application of direct current at all four levels (0.7 to 1.8 mA/cm2) both in the presence and absence of ciprofloxacin. There were no significant differences in log reductions for wells with ciprofloxacin compared to those without at the same current levels. When current exposures were repeated without biofilm or organics in the medium, significant generation of free chlorine was measured. Free chlorine doses equivalent to the 24 hour endpoint concentration for each current level were shown to mimic killing achieved by current application. Current exposure (1.8 mA/cm2) in medium lacking chloride and amended with sulfate, nitrate, or phosphate as alternative electrolytes produced diminished kills of 3, 2, and 0 log reduction, respectively. Direct current also killed Pseudomonas aeruginosa biofilms when NaCl was present. Together these results indicate that electrolysis reactions generating hypochlorous acid from chloride are likely a main contributor to the efficacy of direct current application. A physiologically relevant NaCl concentration is thus a critical parameter in experimental design if direct current is to be investigated for in vivo medical applications.

Microbe(s): avian influenza virus

ABSTRACT – Full Text PDF

The virucidal effects of two types of electrolyzed water, acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW), on avian influenza viruses were studied. Virus titers of the highly pathogenic H5N1 virus and the low-pathogenic H9N2 virus irreversibly decreased by >5-log at 1 min after the viruses were mixed with NEW containing 43 ppm free available chlorine (FAC), but not with NEW containing <17 ppm FAC. The minimum concentration of FAC for a virucidal effect of NEW was estimated at around 40 ppm. In contrast, the virus titers decreased by >5 log at 1 min after the viruses were mixed with AEW, in which the concentration of the FAC ranged from 72 to 0 ppm. Thus, the virucidal effect of AEW did not depend on the presence of FAC. Reverse transcription polymerase chain reaction amplified fragments of the M and NP genes, but not the complete M gene, from RNA extracted from the AEW-inactivated virus. Moderate morphological changes were found under the electron microscope, although no changes were observed in the electrophoresed proteins of the AEW-inactivated virus. No viral genes were amplified from the RNA extracted from the NEW-inactivated virus, regardless of the length of the targeted genes. No viral particles were detected under the electron microscope and no viral proteins were detected by electrophoresis for the NEW-inactivated virus. Thus, this study demonstrated potent virucidal effects of AEW and NEW and differences in the virucidal mechanism of the two types of electrolyzed water.

Microbe(s):  Fungi, Candida albicans

ABSTRACT – Full Text PDF

The fungicidal influencing factors of electrolyzed oxidizing water (EOW) on Candida albicans were investigated by suspension quantitative germicidal tests. Results showed that EOW possessed predominant fungicidal rate on C. albican, as high as consummately 100% after 0.5 min duration of 65.5 mg/L active available chlorine concentration (ACC). The fungicidal effect was promoted proportionally along with ACC but was inhibited by organic interferential bovine serum albumin (BSA). The fungicidal mechanism was also investigated at a biological molecular level by detecting series of biochemical indices. Fluorescent microscopy showed that almost all C. albicans cells were stained red in 1 min, suggesting that cell membrane was one of EOW s action targets. Transmission electron microscopy (TEM) showed that EOW destroyed the cellular protective barriers and imposed some damage upon the nucleus area, which verified EOW s effects on microbial ultra-structures. EOW improved membrane permeabilities with the result that the leakages of cellular inclusions (K+, proteins and DNA) and the conductivity increased rapidly. The dehydrogenase relative activities of C. albicans decreased by 44.0% after 10 min, indicating that EOW also had a destructive effect on cellular dehydrogenase.

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Microbe(s): Bacillus cereus

ABSTRACT – Full Text PDF

Slightly acid electrolyzed water (SAcEW) and ultrasound (US) treatment have emerged as an environmental-friendly antimicrobial agent. However, SAcEW treatment alone shows low antimicrobial efficiency. Therefore, the aim of this study was to develop a hurdle approach that combined SAcEW and US to improve the antimicrobial effect against Bacillus cereus as well as inhibition of the growth on potato. US treatment under different conditions of dip times, acoustic energy densities (AED) and temperatures were conducted to obtain the optimal condition. Our findings demonstrate that 3 min of US with 400 W/L of AED at 40 C treatment (US 40 C) significantly (p 0.05) reduced B. cereus population by 2.3 0.1 log CFU/g with minimal change in the color of potato. In addition, 3 min of SAcEW (pH, 5.35.5 ORP, 958981 mV ACC, 2830 mg/L) simultaneous with US40 C treatment (SAcEW US40 C) an approximately 3.0 log CFU/g reduction in B. cereus. Furthermore, SAcEW US40 C treatment efficiently extended lag time of B. cereus by 0.210.5 hrs, reduced that of specific growth rate by 0.010.23 log CFU/h during storage at different temperatures from 5 to 35 C. Therefore, this combined hurdle technology is capable of improving microbial safety of potato during storage and distribution.

Microbe(s): Escherichia coli

ABSTRACT – Full Text PDF

The food industry has recognized electrolyzed oxidizing water (EOW) as a promising alternative decontamination technique. However, there is not a consensus about the sanitizing mechanism of EOW. In this study, we evaluated the disinfection efficacy of different types of EOW on Escherichia coli. Based on the hypothesis of hydroxyl radicals existing in EOW, in the present study, the hydroxyl radicals existed in slightly acidic electrolyzed water (SAEW) and acidic electrolyzed water (AEW) diluted to different levels were detected quantitatively. An ultraviolet (UV) spectrophotometer was used to scan EOW with different pH values. Accounting for the results of UV scanning to EOW with different pH value and the disinfection efficacy of different types of EOW, it can be concluded that considering the lower chlorine concentration of EOW compared with traditional chlorine disinfectants, the existing form of chlorine compounds rather than the hydroxyl radicals played important role in the disinfection efficacy of EOW.

Microbe(s): Dioscorea spp.

ABSTRACT – Full Text PDF

In this study, the effects of electrolyzed oxidizing water (EOW) on the prevention of enzymatic browning of fresh-cut Jiu Jinhuang Chinese yam were investigated. The yams were immersed in the inhibitors for 25 min at 20 C. Compared with the tap water (TW) treatment, the chromatic attributes were significantly different after 72 h of storage (P < 0.05). The activities of polyphenol oxidase (PPO, EC 1.10.3.1), peroxidase (POD, EC 1.11.1.7), and L-phenylalanine ammonia lyase (PAL, EC 4.3.1.5) were inhibited when measured at 24 h. The contents of phenolic acids, including gallic and chlorogenic acid, in the group treated with the slightly acidic electrolyzed water (SAEW) were higher than those treated with TW and neutral electrolyzed water (NEW). The group treated with NEW had the highest total phenol content (P < 0.05, at 24 h), while the group treated with SAEW had the highest flavonoid content (P < 0.05) during storage. Without being treated with inhibitors, the Km and Vmax values of yam PPO were 0.0044 mol/L and 0.02627 U/min, respectively, and the Ki of samples treated with SAEW and citric acid (CA) were 15.6607 and 2.3969 mol/L, respectively. These results indicate that EOW is beneficial as a browning inhibitor.

Microbe(s): Escherichia coli O157:H7

ABSTRACT – Full Text PDF

Water can be a vector for foodborne pathogen cross-contamination during washing of vegetables if an efficient method of water disinfection is not used. Chlorination is the disinfection method most widely used, but it generates disinfection by-products such as trihalomethanes (THMs). Therefore, alternative disinfection methods are sought. In this study, a dynamic system was used to simulate the commercial conditions of a washing tank. Organic matter and the inoculum of Escherichia coli O157:H7 were progressively added to the wash water in the washing tank. We evaluated the effectiveness of the electrolyzed water (EW) when combining with the addition of salt (1, 0.5 and 0.15 g/L NaCl) on the pathogenic inactivation, organic matter depletion and THM generation. Results indicated that electrolysis of vegetable wash water with addition of salt (0.5 g/L NaCl) was able to eliminate E. coli O157:H7 population build-up and decrease COD accumulation while low levels of THMs were produced.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

The disinfection efficacy of acidic electrolyzed water (AEW) on the fresh-cut vegetables has been recognized. However, the application of AEW in the fresh-keeping of fresh-cut vegetables was limited due to its low pH (<2.7) and higher available chlorine concentration (80200mg/L). In the present study, the microbial reduction and storage qualities of fresh-cut cilantro treated by slightly acidic electrolyzed water (SAEW) were evaluated. The results demonstrated that AEW, mild heat AEW, SAEW and mild heat SAEW treatments could reduce the populations on fresh-cut cilantro at 0 day. However, there were no significant differences among all the treatments during the late storage periods. SAEW and mild heat SAEW treatments could keep the firmness of fresh-cut cilantro and maintain the level of electrolyte leakage in comparison with other treatments. SAEW treatment showed the advantage in keeping the overall quality of fresh-cut cilantro compared with other treatments. SAEW may be a better choice in the storage of fresh-cut cilantro than AEW.

Microbe(s): Escherichia coli O157:H7, Salmonella enteritidis

ABSTRACT – Full Text PDF

Neutral (NEW) and acidic (AEW) electrolyzed water were stored in open or closed glass bottles under light or dark conditions at 20 C for 30 days. The pH, oxidation reduction potential (ORP), electrical conductivity (EC), available chlorine concentration (ACC), dissolved oxygen (DO), and bactericidal efficiency of NEW and AEW were determined during storage or before and after storage, respectively. The pH and EC of NEW and AEW remained unchanged in storage. The ORP, ACC and DO of AEW decreased 22%, 100% and 52% under open storage conditions, respectively. Light had no significant effects on the physicochemical properties of NEW (P > 0.05). Bactericidal efficiency was not markedly affected by storage conditions for NEW, but decreased significantly for AEW under open storage conditions. Electrolyzed water should be stored in closed containers or used immediately to prevent the loss of available chlorine that is one of the main contributing factors for antimicrobial activity.

Microbe(s): Salmonella Typhimurium, Listeria monocytogenes

ABSTRACT – Full Text PDF

Electrolyzed oxidizing (EO) water has proved to be effective against foodborne pathogens attached to cutting boards and poultry surfaces and against spoilage organisms on vegetables; however, its levels of effectiveness against Listeria monocytogenes and Salmonella Typhimurium in cell suspensions have not been compared with those of other treatments. In this study, the oxidation reduction potentials (ORPs), chlorine concentrations, and pHs of acidic and basic EO water were monitored for 3 days at 4 and 25 C after generation. There were no differences between the pHs or ORPs of acidic and basic EO waters stored at 4 or 25 C. However, the free chlorine concentration in acidic EO water stored at 4 C increased after 24 h. In contrast, the free chlorine concentration in acidic EO water stored at 25 C decreased after one day. Cell suspensions of Salmonella Typhimurium and L. monocytogenes were treated with distilled water, chlorinated water (20 ppm), acidified chlorinated water (20 ppm, 4.5 pH), acidic EO water (EOA), basic EO water (EOB), or acidic EO water that was aged at 4 C for 24 h (AEOA) for up to 15 min at either 4 or 25 C. The largest reductions observed were those following treatments carried out at 25 C. EOA and AEOA treatments at both temperatures significantly reduced Salmonella Typhimurium populations by >8 log10 CFU/ml. EOA and AEOA treatments effectively reduced L. monocytogenes populations by >8 log10 CFU/ml at 25 C. These results demonstrate the stability of EO water under different conditions and that EO water effectively reduced Salmonella Typhimurium and L. monocytogenes populations in cell suspensions.

Microbe(s): Bacillus cereus

ABSTRACT – Full Text PDF

To identify the primary component responsible in electrolyzed oxidizing (EO) water for inactivation, this study determined the concentrations of hypochlorous acid (HOCl) and hypochlorite ions (OCl-) and related those concentrations to the microbicidal activity of the water. The ultraviolet absorption spectra were used to determine the concentrations of HOCl and OCl- in EO water and the chemical equilibrium of these species with change in pH and amperage. EO water generated at higher amperage contained a higher chlorine concentration. The maximum concentration of HOCl was observed around pH 4 where the maximum log reduction (2.3 log10 CFU/ml) of Bacillus cereus F4431/73 vegetative cells also occurred. The high correlation (r = 0.95) between HOCl concentrations and bactericidal effectiveness of EO water supports HOCl s role as the primary inactivation agent. Caution should be taken with standard titrimetric methods for measurement of chlorine as they cannot differentiate the levels of HOCl present in EO water of varying pHs.

Microbe(s): Escherichia coli O157:H7

ABSTRACT – Full Text PDF

This study was conducted to investigate the disinfection efficacy of hurdle treatments (thermosonication plus slightly acidic electrolyzed water [SAcEW]) and to develop a model for describing the effect of storage temperatures (4, 10, 15, 20, 25, 30, and 35 C) on the growth of Escherichia coli O157:H7 on fresh-cut kale treated with or without (control) thermosonication combined with SAcEW. The hurdle treatments of thermosonication plus SAcEW had strong bactericidal effects against E. coli O157:H7 on kale, with approximately 3.3-log reductions. A modified Gompertz model was used to describe growth parameters such as specific growth rate (SGR) and lag time (LT) as a function of storage temperature, with high coefficients of determination (R2 > 0.98). SGR increased and LT declined with rising temperatures in all samples. A significant difference was found between the SGR values obtained from treated and untreated samples. Secondary models were established for SGR and LT to evaluate the effects of storage temperature on the growth kinetics of E. coli O157:H7 in treated and untreated kale. Statistical evaluation was carried out to validate the performance of the developed models, based on the additional experimental data not used for the model development. The validation step indicated that the overall predictions were inside the acceptable prediction zone and had lower standard errors, indicating that this new growth model can be used to assess the risk of E. coli O157:H7 contamination on kale.

Microbe(s): Listeria monocytogenes

ABSTRACT – Full Text PDF

This study evaluated the efficacy of thermosonication combined with slightly acidic electrolyzed water (SAcEW) on the shelf life extension of fresh-cut kale during storage at 4 and 7 C. Each kale (10 0.2 g) was inoculated to contain approximately 6 log CFU/g of Listeria monocytogenes. Each inoculated or uninoculated samples was dip treated at 40 C for 3 min with deionized water, thermosonication (400 W/L), SAcEW (5 mg/L), sodium chlorite (SC; 100 mg/L), sodium hypochlorite (SH; 100 mg/L), and thermosonication combined with SAcEW, SC, and SH (TS + SAcEW, TS + SC, and TS + SH, respectively). Growths of L. monocytogenes and spoilage microorganisms and changes in sensory (overall visual quality, browning, and off-odour) were evaluated. The results show that lag time and specific growth rate of each microorganism were not significantly (P > 0.05) affected by treatment and storage temperature. Exceeding the unacceptable counts of spoilage microorganisms did not always result in adverse effects on sensory attributes. This study suggests that TS + SAcEW was the most effective method to prolong the shelf life of kale with an extension of around 4 and 6 days at 4 and 7 C, respectively, and seems to be a promising method for the shelf life extension of fresh produce.

Microbe(s): Escherichia coli O157:H7

ABSTRACT – Full Text PDF

The purpose of this study was to evaluate and model the growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to a neutral electrolyzed water (NEW) treatment, packaged in passive modified atmosphere and subsequently stored at different temperatures (4, 8, 13, 16 C) for a maximum of 27 days. Results indicated that E. coli O157:H7 was able to grow at 8, 13, and 16 C, and declined at 4 C. However at 8 C, the lag time lasted 19 days, above the typical shelf-life time for this type of products. A secondary model predicting growth rate as a function of temperature was developed based on a square-root function. A comparison with literature data indicated that the growth predicted by the model for E. coli O157:H7 was again lower than those observed with other disinfection treatments or packaging conditions (chlorinated water, untreated product, NEW, etc.). The specific models here developed might be applied to predict growth in products treated with NEW and to improve existing quantitative risk assessments.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

Product decontamination is one of the most important processes of the hygienic practice in food industries such as Minimally Processed Vegetables (MPV) plants and sodium hypochlorite (NaOCl) solutions are commonly used as a biocide for disinfection. Although it may be corrosive and irritating when compared to , reducing the free chlorine concentration needed to sanitize salads, also decreasing water consumption whilst taking into account environmental and food quality impacts.

Microbe(s): Listeria monocytogenes

ABSTRACT – Full Text PDF

The presence of Listeria monocytogenes in food processing environment is a risk of food contamination by persistent cells due to their ability to attach to stainless steel and other surfaces. We aimed to study biofilms formation of lux-tagged L. monocytogenes EGDe on stainless steel surfaces and their control using neutral electrolyzed water (NEW), where biofilms development was monitored using destructive and non-destructive microscopy techniques. The development of biofilms was monitored for 5 days on stainless steel chips. We used two sources of NEW, commercial (NEW-1) and from a prototype (NEW-2) for treatments of free and biofilm L. monocytogenes EGDe cells. Complete inhibition of L. monocytogenes EGDe free cells was observed after 1 min contact time for both NEW sources, but NEW-1 concentration used (9 mg/L total available chlorine, TAC) was 1.8 times higher. Cells within biofilms were more resistant to NEW compared to planktonic cells. Same concentration of both NEW sources (70 mg/L TAC) exhibited complete inhibition of biofilm cells after 3 min contact time. However, using a sub-lethal dose of 40 mg/L TAC, NEW-2 reduced about 2 log CFU/cm2 biofilm cells while NEW-1 inhibited 0.3 log CFU/cm2 only. Biofilms formation and antagonistic effect of NEW could be visualized by epifluorescence and scanning electron microscopy, revealing significant biofilms structure. The disinfectant effect of NEW may be attributed to the combined antimicrobial effect of available chlorine and high ORP exhibited by its oxidizing compounds. NEW does not promote metal equipment corrosion due to its neutral pH, and is also environmentally friendly.

Microbe(s): Listeria monocytogenes

ABSTRACT – Full Text PDF

This study investigates the resistance of Listeria monocytogenes biofilms on stainless steel surfaces to electrolyzed oxidizing (EO) water. A direct agar overlay method was used to estimate the attached bacteria on stainless steel coupons after an EO water treatment. A scraping method was also used to quantify the adherent cell populations after the EO water treatment. The stainless steel surface allowed 10 to 15% of the surface area to be covered by Listeria biofilm when the inoculated stainless steel coupon was incubated in 10% tryptic soy broth (TSB) at 23C for 48 h. When the stainless steel coupons containing adherent cells were treated with EO water (56 mg/L of residual chlorine) for 10, 30, 60, 180, and 300 s, adherent cell populations (10.3 log10 CFU/coupon) were reduced with increasing treatment time. Although the direct agar overlay methods do not quantify survival of single bacteria, only one to five cell clumps per coupon survived after 300 s of the EO water treatment. Using the scraping method, the adherent cell population on the stainless steel coupons was reduced by about 9 log cycles after 300 s of EO water treatment.

Microbe(s): Escherichia coli O157:H7

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Effect of ultrasonication (40 kHz) to enhance low concentration electrolyzed water (LcEW) efficacy for microbial decontamination on lettuce leaves was investigated. Lettuce was separately treated with LcEW, ultrasonication, LcEW combined with ultrasonication, LcEW followed by ultrasonication, and ultrasonication followed by LcEW for 1, 3, and 5 min for each step at room temperature. The highest reduction (2.3 log CFU/g) in total bacteria count (TBC) was resulted from ultrasonication followed by LcEW. Subsequently, the effect of temperature was studied resulting in 2.6 and 3.18 log CFU/g reduction of TBC and Escherichia coli O157:H7 respectively, in 3 min ultrasonication followed by 3 min LcEW treatment at 40 C. This optimum treatment also prevented lettuce from reaching 7.0 log CFU/g in TBC until the end of the 6 day storage at 10 C. Therefore, this newly developed approach may result in improved microbiological safety and enhanced shelf life of produce.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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Slightly acidic electrolyzed water (SAEW) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. However, microbial reductions from SAEW treatment are not enough to ensure produce safety. Therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. This study examined the microbicidal activity of SAEW (pH 5.2-5.5, oxidation reduction potential 500-600 mV, available chlorine concentration 21-22 mg/l) on Chinese cabbage, lettuce, sesame leaf and spinach, four common fresh vegetables in Korea under same laboratory conditions. Subsequently, effects of ultrasonication and water wash to enhance the sanitizing efficacy of SAEW were studied, separately. Finally, an optimized simple and easy approach consisting of simultaneous SAEW treatment with ultrasonication (3 min) followed by water wash (150 rpm, 1 min) was developed (SAEW + US-WW). This newly developed hurdle treatment significantly enhanced the microbial reductions compared to SAEW treatment alone, SAEW treatment with ultrasonication (SAEW + US) and SAEW treatment followed by water wash (SAEW-WW) at room temperature (23 2 C). Microbial reductions of yeasts and molds, total bacteria count and inoculated Escherichia coli O157:H7 and Listeria monocytogenes were in the range of 1.76-2.8 log cfu/g on different samples using the new hurdle approach.

Microbe(s): E. coli O157:H7

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Increased interest in blueberries due to their nutritional and health benefits has led to an increase in consumption. However, blueberries are consumed mostly raw or minimally processed and are susceptible to microbial contamination like other type of fresh produce. This study was, therefore, undertaken to evaluate the efficacy of electrostatic spray of electrolyzed oxidizing (EO) water, UV light, ozone, and a combination of ozone and UV light in killing Escherichia coli O157:H7 on blueberries. A 5-strain mixture of E. coli O157:H7 were inoculated on the calyx and skin of blueberries and then subjected to the treatments. Electrostatic EO water spray reduced initial populations of E. coli O157:H7 by only 0.13 to 0.24 log CFU/g and 0.88 to 1.10 log CFU/g on calyx and skin of blueberries, respectively. Ozone treatment with 4000 mg/L reduced E. coli O157:H7 by only 0.66 and 0.72 log CFU/g on calyx and skin of blueberries, respectively. UV light at 20 mW/cm2 for 10 min was the most promising single technology and achieved 2.14 and greater than 4.05 log reductions of E. coli O157:H7 on the calyx and skin of blueberries, respectively. The combination treatment of 1 min ozone and followed by a 2 min UV achieved more than 1 and 2 log additional reductions on blueberry calyx than UV or ozone alone, respectively.

Microbe(s): Total Microbial Count

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The efficacy of slightly acidic electrolyzed water (SAEW, 20 mg/l of available chlorine) and sodium hypochlorite solution (NaClO, 120 mg/l of available chlorine) used as potential sanitizers for fresh-cut cucumbers was evaluated. SAEW with a near-neutral pH value (5.0 to 6.5) and lower available chlorine concentration (ACC) had an equivalent or higher efficiency to reduce microbial counts on the cucumbers compared to NaClO solution. A 5-minute treatment of SAEW and NaClO solution significantly reduced the indigenous aerobic bacteria on cucumbers by 1.62 and 1.51 log10 CFU/g, and molds and yeasts by 1.35 and 1.12 log10 CFU/g, respectively (P < 0.05). The reduction of microbial counts on cucumbers by tap water was markedly less than that by SAEW and NaClO solution (P < 0.05). Results indicate that SAEW provides an alternative technique for sanitization of fresh-cut vegetables with environmentally friendly broad spectrum microbial decontamination.

Microbe(s): Escherichia coli, Bacillus subtilis

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The efficacy of slightly acidic electrolyzed water (SAEW) for reducing microbial contamination on fresh-cut cilantro was investigated in this study. The impacts of SAEW on the microbes of cilantro samples inoculated with two kinds of bacteria (Escherichia coli O78 and Bacillus subtilis 1.1849) were evaluated in comparison with NaClO solution and acidic electrolyzed water (AEW). Dipping with AEW, SAEW and NaClO solutions for 5 min resulted in a reduction in populations of E. coli O78 from 6.38 to 4.93, 3.89 and 4.88 log10 cfu/g and in populations of B. subtilis from 6.52 to 5.02, 4.98, 4.63 log10 cfu/g, respectively, The similar results were found that the populations on cilantro inoculated the mixture of two microbes of E. coli O78 treated with AEW, SAEW and NaClO solutions decreased to 4.15, 3.99, 5.10 log10 cfu/g, respectively, and the populations of B. subtili on cilantro decreased to 5.08,4.97,4.82 log10 cfu/g, respectively. The efficacies of SAEW wash in reducing natural micro flora on fresh-cut cilantro were studied. The results showed SAEW had strong disinfection ability to reduce the microbe population of fresh-cut cilantro and could be an alternative of AEW and NaClO solutions.

Microbe(s): Listeria monocytogenes

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Electrolyzed oxidizing water has been estimated that it has strong bactericidal activity and has been widely used as a disinfectant for inactivating microbial organisms. The combined effects of temperature (15 35C), chlorine concentration of electrolyzed oxidizing water (30 70 ppm) and treatment time (1 5 min) on the reduction of Listeria monocytogenes in lettuce were investigated. Reductions of 1.39 2.79 log10 cfu/g were observed in different combinations of the three factors. Also, a quadratic equation for L. monocytogenes inactivation kinetic was developed by multiple regression analysis using response surface methodology. The predicted values were shown to be significantly in good agreement with experimental values because the adjusted determination coefficient (inline image) was 0.9578 and the level of significance was P < 0.0001. Besides, average mean deviation (E%), bias factor (Bf) and accuracy factor (Af), which are validation indicators of the model were 0.0218, 1.0003 and 1.0220, respectively. Thus, predicted model showed a good correlation between the experimental and predicted values, indicating success at providing reliable predictions of L. monocytogenes growth in lettuce.

Microbe(s): Total Microbial Count

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Electrolyzed functional water possesses a wide variety of antimicrobial activities. Electrolyzed functional water, which used to take place of tap water in producing mung bean sprouts, was studied in this paper. The results showed that electrolyzed water can not only reduce the quantity of microorganism on the surface of mung bean sprouts, but also promote the growth of sprouts. Further research showed that electrolyte leakage rate of mung bean soaked in electrolyzed water was the lowest, while the catalase s activity of mung bean soaked in electrolyzed water was the highest. All of these contribute to the high activity of mung bean.

Microbe(s): Total Microbial Count, Total Aerobic Bacteria, Coliforms, Escherichia coli

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The effectiveness of electrolyzed oxidizing anode (EOA) water (oxidation-reduction potential, 1,120 mV; pH 2.0) as a sanitizer for use in abattoirs was compared with the iodophor (IOD) Mikroklene (25 ppm), a sanitizer approved for use by regulatory authorities in Canada and the United States. A total of 240 swab (100 cm2) samples were obtained from 4 sites on the kill floor and 16 sites in the secondary processing areas, during two visits within a 4-week period to each of three meat packing plants, processing < or =50 animals per week. Swabs were obtained 12 h after the application of IOD and EOA and were analyzed for the presence of total aerobic bacteria, total coliforms, and total Escherichia coli. Total aerobic bacteria (log CFU/ 100 cm2) recovered from the 20 sample sites were lower (P < 0.0001) in EOA as compared with IOD (2.94 +/- 0.12 versus 3.75 +/- 0.12, respectively). Plant A was 1.5 times more likely (P < 0.0001) to have a sampling site positive for the presence of coliforms and E. coli than plants B and C. There was no difference (P > 0.05) between treatment IOD or EOA in the likelihood of obtaining a positive sample for the presence of total coliforms or E. coli among the three plants. When the kill floor and secondary processing areas are compared, the likelihood of obtaining a sample positive for coliforms or E. coli was similar (P > or = 0.05). Results indicate that EOA was more effective than IOD in reducing populations of total aerobic bacteria on equipment surfaces in the three meat packing plants studied. Because the likelihood of obtaining a positive sample for coliforms or E. coli in EOA as compared with IOD was similar, EOA may be a suitable alternative or complement to IOD as a sanitizer in small- to medium-sized abattoirs. Additional research is required to further evaluate the effectiveness of EOA to sanitize processing equipment on the basis of subsequent isolation of aerobes, coliforms, and E. coli from meat products.

Microbe(s): Fungi, Botrytis cinerea, Monilina fructicola

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This study evaluated the potential of near-neutral (pH 6.36.5) electrolyzed oxidizing water (EO water) to inactivate pure cultures of Botrytis cinerea and Monilinia fructicola and to mitigate fungal infection of these organisms on fruit surfaces. Treatment of these organisms, in pure culture, with EO water at concentrations of 25, 50, 75, and 100 ppm total residual chlorine (TRC) and 10 min of contact time resulted in a 6 log10 spores/mL reduction of both organisms. A dip treatment or a dip and daily spray treatment of EO water were used to evaluate its ability to prevent or delay the onof surface infection on fruit during postharvest packaging and in retail shelf environments. A 10 minute dip treatment of surface inoculated peaches (M. fructicola) in EO water prevented infection for 3 days and resulted in a 12.5 incidence of infection and a disease severity rating of 6 after 5 days of storage at 25 C. Dipping of green table grapes inoculated with B. cinerea into EO water prevented infection for 7 days and resulted in a 1 incidence of infection and a disease severity rating of 2 after 10 days of storage at 25 C. A dip and daily spray of peaches with EO water prevented infection for 12 days and resulted in a 10 incidence of infection and a 6 disease severity after 14 days of storage at 25 C. A dip and daily spray of grapes with EO water prevented infection for 24 days and resulted in a 2 incidence of infection and a disease severity rating of 2 after 26 days of storage at 25 C. The results from this study suggest that these solutions may prove to be effective for postharvest sanitation of fruit surfaces prior to packaging and may increase the shelf life of the fruit in commercial settings.

Microbe(s): Total Microbial Count

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Pre-treatment steps of fresh produce as Saengshik raw materials are followed by initial clean-up, dipping, primary washing, and cutting. Hypochlorous acid solution was applied in the dipping step to reduce natural microflora. Also, procedures were changed by cutting, dipping and then primary washing, and the efficacy of hypochlorus acid was evaluated. Potatoes, carrots, kales, and angelicas were submerged in water or 100 ppm of hypochlorous acid for 5 min. After initial clean-up, the aerobic plate counts of potatoes, carrots, kales and angelicas were 4.7, 5.3, 5.6, and 5.7 log CFU/g, respectively. When samples were submerged into water, it only reduced the population of natural microflora by 0.2 to 1.1 log CFU/g, whereas when treated with hypochlorous acid, it reduced the population by 0.5 to 2.8 log CFU/g. Reductions of natural microflora in green leafy vegetables were more highly achieved than bulbs such as potatoes and carrots. However, the numbers of natural microflora were increased after cutting step. To control the cross contamination at the cutting process, the process was changed as follows: initial clean-up, cutting, dipping in hypochlorous acid, and then primary washing. It showed effective reduction of the population by 2.3 to 3.2 log CFU/g. Hypochlorous acid solution could be useful as a sanitizer for surface washing of fresh vegetables.

Microbe(s): Pseudomonas fluorescens, Pantoea agglomerans or Rahnella aquatilis

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The efficacy of Electrolysed Oxidising Water (EOW) for inactivating spoilage microorganisms in process water and on minimally processed vegetables was investigated. The direct effect of EOW on three important spoilage bacteria namely; Pseudomonas fluorescens, Pantoea agglomerans or Rahnella aquatilis was determined by inoculating tap water or artificial process water with approximately 8 log CFU/ml pure culture and electrolysing the resultant solutions. The three bacteria were each reduced to undetectable levels at low (0.5 A) and relatively higher levels (1.0 A) of current in tap water and artificial process water , respectively. The residual effect of EOW on P. fluorescens, P. agglomerans or R. aquatilis was determined by incubating at room temperature 1 ml (approximately 9 log CFU/ml) pure culture suspensions in 9 ml of EOW-T (EOW produced from tap water), EOW-A (EOW produced from artificial process water supplemented with approximately 60.7 mg Cl /l and 39.3 mg Na+/l) or deionised water (control) for 0, 15, 45 or 90 min. The bactericidal activity of both EOW-T and EOW-A increased with the concentration of free oxidants and incubation period and the three bacteria were completely reduced at free oxidants-incubation period combinations of 3.88 mg/l 45 min and 5.1 mg/l 90 min in EOW-T and EOW-A, respectively. Two types of industrial vegetable process water; salad-mix and soup process water, which had each a total psychrotrophic count of approximately 8 log CFU/ml were then electrolysed. Without any NaCl addition, only 1.2 and 2.1 log reductions of the psychrotrophs in soup and salad-mix process water was attained respectively. Supplementation of the process water with approximately 60.7 mg Cl /l and 39.3 mg Na+/l afterwards resulted in complete reduction of the psychrotrophic count in both process waters, but soup process water required relatively higher levels of current compared to salad-mix water. Finally, fresh-cut lettuce was washed in EOW-T containing 3.62 mg free oxidants/l, EOW-IP (EOW produced from industrial process water) containing 2.8 mg free oxidants/l or tap water (control) for 1 or 5 min. Washing the vegetables for 1 min in EOW-T resulted in 1.9, 1.2, and 1.3 log reductions of psychrotrophs, lactic acid bacteria and Enterobacteriacae, respectively, which increased to 3.3, 2.6, and 1.9 log reductions after washing for 5 min instead. EOW-IP tested in this work had no bactericidal effect on the microflora of fresh-cut lettuce. Electrolysis could therefore be used to decontaminate process water for vegetable pre-washing and to sanitise tap water for final rinsing of vegetables, respectively.

Microbe(s): Salmonella

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Studies have demonstrated that electrolyzed oxidizing (EO) water is effective in reducing foodborne pathogens on fresh produce. This study was undertaken to determine the efficacy of EO water and two different forms of chlorinated water (chlorine water from Cl2 and Ca(OCl)2 as sources of chlorine) in inactivating Salmonella on alfalfa seeds and sprouts. Tengram sets of alfalfa seeds inoculated with a five-strain cocktail of Salmonella (6.3 104 CFU/g) were subjected to 90 ml of deionized water (control), EO water (84 mg/liter of active chlorine), chlorine water (84 mg/liter of active chlorine), and Ca(OCl)2 solutions at 90 and 20,000 mg/liter of active chlorine for 10 min at 24 2 C. The application of EO water, chlorinated water, and 90 mg/liter of Ca(OCl)2 to alfalfa seeds for 10 min reduced initial populations of Salmonella by at least 1.5 log10 CFU/g. For seed sprouting, alfalfa seeds were soaked in the different treatment solutions described above for 3 h. Ca(OCl)2 (20,000 mg/liter of active chlorine) was the most effective treatment in reducing the populations of Salmonella and non-Salmonella microflora (4.6 and 7.0 log10 CFU/g, respectively). However, the use of high concentrations of chlorine generates worker safety concerns. Also, the Ca(OCl)2 treatment significantly reduced seed germination rates (70% versus 90 to 96%). For alfalfa sprouts, higher bacterial populations were recovered from treated sprouts containing seed coats than from sprouts with seed coats removed. The effectiveness of EO water improved when soaking treatments were applied to sprouts in conjunction with sonication and seed coat removal. The combined treatment achieved 2.3- and 1.5-log10 CFU/g greater reductions than EO water alone in populations of Salmonella and non-Salmonella microflora, respectively. This combination treatment resulted in a 3.3-log10 CFU/g greater reduction in Salmonella populations than the control (deionized water) treatment.

Microbe(s): Total Microbial Count

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The disinfectant effect of acidic electrolyzed water (AcEW), ozonated water, and sodium hypochlorite (NaOCl) solution on lettuce was examined. AcEW (pH 2.6; oxidation reduction potential, 1140 mV; 30 ppm of available chlorine) and NaOCl solution (150 ppm of available chlorine) reduced viable aerobes in lettuce by 2 log CFU/g within 10 min. For lettuce washed in alkaline electrolyzed water (AlEW) for 1 min and then disinfected in AcEW for 1 min, viable aerobes were reduced by 2 log CFU/g. On the other hand, ozonated water containing 5 ppm of ozone reduced viable aerobes in lettuce 1.5 log CFU/g within 10 min. It was discovered that AcEW showed a higher disinfectant effect than did ozonated water significantly at P < 0.05. It was confirmed by swabbing test that AcEW, ozonated water, and NaOCl solution removed aerobic bacteria, coliform bacteria, molds, and yeasts on the surface of lettuce. Therefore, residual microorganisms after the decontamination of lettuce were either in the inside of the cellular tissue, such as the stomata, or making biofilm on the surface of lettuce. Biofilms were observed by a scanning electron microscope on the surface of the lettuce treated with AcEW. Moreover, it was shown that the spores of bacteria on the surface were not removed by any treatment in this study. However, it was also observed that the surface structure of lettuce was not damaged by any treatment in this study. Thus, the use of AcEW for decontamination of fresh lettuce was suggested to be an effective means of controlling microorganisms.

Microbe(s): Total Microbial Count

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The effect of electrolyzed water on total microbial count was evaluated on several fresh-cut vegetables. When fresh-cut carrots, bell peppers, spinach, Japanese radish, and potatoes were treated with electrolyzed water (pH 6.8, 20 ppm available chlorine) by dipping, rinsing, or dipping/blowing, microbes on all cuts were reduced by 0.6 to 2.6 logs CFU/g. Rinsing or dipping/blowing were more effective than dipping. Electrolyzed water containing 50 ppm available chlorine had a stronger bactericidal effect than that containing 15 or 30 ppm chlorine for fresh-cut carrots, spinach, or cucumber. Electrolyzed water did not affect tissue pH, surface color, or general appearance of fresh-cut vegetables.

Microbe(s): Total Microbial Count, Coliforms, Bacillus cereus

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Effects of storage temperature (1, 5, and 10 C) on growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) on acidic electrolyzed water (AcEW)-treated fresh-cut lettuce and cabbage were determined. A modified Gompertz function was used to describe the kinetics of microbial growth. Growth data were analyzed using regression analysis to generate best-fit modified Gompertz equations, which were subsequently used to calculate lag time, exponential growth rate, and generation time. The data indicated that the growth kinetics of each bacterium were dependent on storage temperature, except at 1 C storage. At 1 C storage, no increases were observed in bacterial populations. Treatment of vegetables with AcEW produced a decrease in initial microbial populations. However, subsequent growth rates were higher than on nontreated vegetables. The recovery time required by the reduced microbial population to reach the initial (treated with tap water [TW]) population was also determined in this study, with the recovery time of the microbial population at 10 C being <3 days. The benefits of reducing the initial microbial populations on fresh-cut vegetables were greatly affected by storage temperature. Results from this study could be used to predict microbial quality of fresh-cut lettuce and cabbage throughout their distribution.

Microbe(s): Microbe(s): Listeria monocytogenes, Salmonella typhimurium, Campylobacter coli

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To date, the effectiveness of electrolyzed oxidizing (EO) water against bacteria associated with fresh pork has not been determined. Using a hand-held, food-grade garden sprayer, distilled water (W), chlorinated water (CL; 25 ppm), 2% lactic acid (LA), acidic EO water (EOA), or aged acidic EO water (AEOA; stored at 4 C for 24 h) was sprayed (15 s) onto pork bellies inoculated with feces containing Listeria monocytogenes (LM), Salmonella typhimurium (ST), and Campylobacter coli (CC). Remaining bacterial populations were determined immediately following treatment, after 2 days of aerobic storage, and again after 5 days of vacuum-packaged, refrigerated storage (day 7). While LA and EOA significantly reduced (p<0.05) populations of CC at days 0 and 7, there was no significant difference (p>0.05) between antimicrobial treatments when applied to pork inoculated with ST or LM. This study demonstrates that a 15-s spray with EOA has the ability to reduce CC associated with fresh pork surfaces. However, longer contact times may be necessary to reduce other microbial contaminants.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.

Microbe(s): Botryosphaeria berengeriana

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Chlorination presents one of the few chemical options available to help manage postharvest decay. Electrolyzed oxidizing (EO) water, containing free chlorine, is the product of a new concept developed by scientists in Japan. The effectiveness of pear (Pyrus communis L.) immersion in EO water on the control of Bot. rot on European pear, cv. La-France, was investigated. Four independent experiments were carried out. A wound was found necessary for infection. Wounded fruit were inoculated with 20 l spore suspension of 5 105 conidia/ml of Botryosphaeria berengeriana, incubated for 4 h, immersed in EO water, and held at 20 C, 90% relative humidity (simulated retail conditions) for ripening and disease development. No chlorine-induced phytotoxicity was observed on the treated fruit. EO water suppressed the incidence and disease severity. The minimum incidence and severity were recorded for a 10-min immersion period. This study revealed that EO water is an effective surface sanitizer.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

The disinfectant effect of acidic electrolyzed water (AcEW), ozonated water, and sodium hypochlorite (NaOCl) solution on lettuce was examined. AcEW (pH 2.6; oxidation reduction potential, 1140 mV; 30 ppm of available chlorine) and NaOCl solution (150 ppm of available chlorine) reduced viable aerobes in lettuce by 2 log CFU/g within 10 min. For lettuce washed in alkaline electrolyzed water (AlEW) for 1 min and then disinfected in AcEW for 1 min, viable aerobes were reduced by 2 log CFU/g. On the other hand, ozonated water containing 5 ppm of ozone reduced viable aerobes in lettuce 1.5 log CFU/g within 10 min. It was discovered that AcEW showed a higher disinfectant effect than did ozonated water significantly at P < 0.05. It was confirmed by swabbing test that AcEW, ozonated water, and NaOCl solution removed aerobic bacteria, coliform bacteria, molds, and yeasts on the surface of lettuce. Therefore, residual microorganisms after the decontamination of lettuce were either in the inside of the cellular tissue, such as the stomata, or making biofilm on the surface of lettuce. Biofilms were observed by a scanning electron microscope on the surface of the lettuce treated with AcEW. Moreover, it was shown that the spores of bacteria on the surface were not removed by any treatment in this study. However, it was also observed that the surface structure of lettuce was not damaged by any treatment in this study. Thus, the use of AcEW for decontamination of fresh lettuce was suggested to be an effective means of controlling microorganisms.

Microbe(s): Listeria monocytogenes

ABSTRACT – Full Text PDF

Experiments were conducted to determine the effectiveness of acidic (EOA) or basic electrolyzed oxidizing (EOB) water, alone or in combination, on ready-to-eat (RTE) meats to reduce Listeria monocytogenes (LM). Frankfurters or ham surfaces were experimentally inoculated with LM and subjected to dipping or spraying treatments (25 or 4 C for up to 30 min) with EOA, EOB, and other food grade compounds. LM was reduced the greatest when frankfurters were treated with EOA and dipped at 25 C for 15 min. A combination spray application of EOB/EOA also resulted in a slight reduction of LM on frankfurters and ham. However, reductions greater than 1 log CFU/g were not observed for the duration of the study. Even with a prolonged contact time, treatments with EOA or EOB were not enough to meet regulatory requirements for control of LM on RTE meats. As such, additional studies to identify food grade antimicrobials to control the pathogen on RTE meats are warranted.

Microbe(s): Salmonella, Listeria, Campylobacter, Escherichia coli

ABSTRACT – Full Text PDF


In 1999 the foodborne pathogens Salmonella, Listeria, Campylobacter, and Escherichia coli (both O157 and non-O157) were estimated to cause more than 6 million illnesses and approximately 9000 deaths each year. However, the most recent Centers for Disease Control and Prevention report on the sources and incidence of foodborne disease, released in 2004, has shown a dramatic decrease in E. coli O157:H7 infections. Since raw beef products are the most frequently foodborne sources of these pathogens, the results of this report demonstrate that the microbiological quality of raw beef has improved greatly. During the intervening years, post-harvest interventions have continually improved, with new attention to hide decontamination and innovative treatments of carcasses. In addition, a system to hold and test beef trim or ground beef for E. coli O157:H7 before its release into commerce has provided an even greater level of safety. In this paper, we review the latest information on the prevalence of E. coli O157:H7 and other pathogens on beef, the evidence identifying the hide as the primary source of pathogens on beef carcasses, the efficacy of various hide and carcass interventions, and other developments that have led or have the potential to lead to even greater improvements in the microbial quality of beef.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

The main factor contributing to the disinfecting potential of acidic electrolyzed water (AcEW) is deduced to be the oxidizing power of available chlorine. In this study, we compared the reliability of two different methods for measuring the available chlorine concentration (ACC). Several AcEW solutions with different levels of ACC to which various reducing agents (ascorbic acid, ammonium iron (II) sulfate, and iron (II) chloride) had been added were prepared. These ACC levels were quantified by iodometry and the DPD (N, N-diethyl-p-phenylenediamine) method. In the case of AcEW with iron (II) ions, iodometry did not show the correct ACC. On the other hand, the DPD method correctly quantified ACC even in the case of AcEW with iron (II) ions. Thus, the DPD method is an appropriate method for measuring ACC in AcEW. Moreover, we investigated the effect of the available chlorine concentration (ACC) in AcEW on its disinfecting potential. First, we examined the disinfectant effects of AcEW on shredded vegetables. We found that there was no difference in the disinfectant effects between AcEW with high ACC (40ppm) and low ACC (0.4ppm). The similar effect was detected in AcEW with 0ppm of ACC, a solution that seemed to be the same as hydrochloric acid. Moreover, tap water with pH adjusted to 2.4 showed the same disinfectant effect as that of AcEW. These results indicated that AcEW is a solution in which available chlorine is activated in a low pH condition. Next, we examined the disinfectant effects of AcEW on a suspension obtained from shredded vegetables in vitro. The disinfecting potential became weaker, but did not completely disappear, when ACC was reduced to 0ppm. Thus, AcEW with low ACC could be used to disinfect shredded vegetables, although the disinfecting potential of AcEW would become weak. When the effective concentration of Acc was examined, it was found that the AcEW with ACC of less than 20ppm did not have sufficient disinfectant potential. Moreover, it was found that high ORP (above 1000mV) does not contribute to disinfecting potential. Thus, the lower limit of ACC in AcEW for AcEW to exert a sufficient disinfectant effect will be 20ppm.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

ABSTRACT – Full Text PDF

The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.

Microbe(s): Staphylococcus aureus, Escherichia coli

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The article focuses on investigation of the effects of usage of acidic electrolyzed water (AEW) with different sodium chloride concentration (0.001, 0.01, and 0.1) for the preparation of carrageenan and gelatine hydrosols and hydrogels. To determine physiochemical properties of hydrosols, the pH, oxidation-reduction potential (ORP), available chloride concentration (ACC) and rheological parameters such us gelation and flow temperatures were measured. The samples were also 0.1 w/v). These results suggest that hydrogels and hydrosols incorporated with AEW may be used for food preservation.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium

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This study evaluated the efficacy of the individual treatments (slightly acidic electrolyzed water [SAcEW] or fumaric acid [FA]) and their combination to reduce Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium in fresh pork as well as to study the shelf life and sensory quality (color, odor, and texture) of pork during storage at 4 and 10 C. The inoculated pork samples (10 g) were dipped for 3 min in each treatment (tap water [TW], SAcEW, strong acidic electrolyzed water [StAEW], 0.5% FA, or SAcEW + 0.5% FA) with or without mild heat (40 C). Decontamination of fresh pork with SAcEW +0.5% FA at 40 C for 3 min showed greater bactericidal effect compared to other treatments, which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, S. aureus, and S. Typhimurium by 2.59, 2.69, 2.38, and 2.99 log CFU/g, respectively. This combined treatment significantly (P < 0.05) yielded in a longer lag time of naturally occurring bacteria (TBC) on pork stored at 4 C. This combined treatment also prolonged the shelf life of pork up to 6 days and 4 5 days when stored at 4 C and 10 C, respectively, compared to those of the untreated pork. The results suggest that the combined treatment of SAcEW + 0.5% FA has potential as a novel method to enhance the microbial safety and quality of fresh pork.

Microbe(s): Escherichia coli O157:H7 Salmonella Typhimurium, Listeria monocytogenes

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The bactericidal efficacy of acidic electrolyzed oxidizing water (AC-EW) (pH = 2.30, free chlorine = 38 ppm) and sterile distilled water (DW) on three pathogens (Escherichia coli O157:H7 Salmonella Typhimurium, and Listeria monocytogenes) inoculated on raw trout skin, chicken legs and beef meat surfaces was evaluated. The decontaminating effect of AC-EW and DW was tested for 0 (control), 1, 3, 5 and 10 min at 22 C. AC-EW significantly (P < 0.05) reduced the three pathogens in the inoculated samples compared to the control and DW. The level of reduction ranged between ca.1.5 1.6 logs for E. coli O157:H7 and S. Typhimurium in the inoculated foods. However, AC-EW exhibited less bactericidal effect against L. monocytogenes (1.1 1.3 logs reduction). AC-EW elicited about 1.6 2.0 log reduction in the total mesophilic count. Similar treatment with DW reduced pathogens load by ca. 0.2 1.0 log reduction and total mesophiles by ca. 0.5 0.7 logs. No complete elimination of the three pathogens was obtained using AC-EW possibly because of the level of organic matter and blood moving from food samples to the AC-EW solution. This study demonstrates that AC-EW could considerably reduce common foodborne pathogens in fish, chicken and beef products.

Microbe(s): Pseudomonas spp.,Shewanella spp.

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The bacterial species and specific spoilage organisms associated with the Southern Australian King George Whiting (KGW) and Tasmanian Atlantic Salmon (TAS), and the efficacy of a HOCl-containing water-based sanitization product (Electro-Chemically Activated Solution, by ECAS4) in extending the shelf life of KGW and TAS fillets were evaluated. Fillets were washed with an ECAS4 solution containing either 45 ppm or 150 ppm of free chlorine and bacterial species enumerated on out many of the disadvantages of currently approved biocides.

Microbe(s): Listeria monocytogenes, Escherichia coli, Vibrio parahaemolyticus

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Electrolysed oxidising water (E.O. water) is produced by electrolysis of sodium chloride to yield primarily chlorine based oxidising products. At neutral pH this results in hypochlorous acid in the un-protonated form which has the greatest oxidising potential and ability to penetrate microbial cell walls to disrupt the cell membranes. E.O. water has been shown to be an effective method to reduce microbial contamination on food processing surfaces. The efficacy of E.O. water against pathogenic bacteria such as Listeria monocytogenes, Escherichia coli and Vibrio parahaemolyticus has also been extensively confirmed in growth studies of bacteria in culture where the sanitising agent can have direct contact with the bacteria. However it can only lower, but not eliminate, bacteria on processed seafoods. More research is required to understand and optimise the impacts of E.O. pre-treatment sanitation processes on subsequent microbial growth, shelf life, sensory and safety outcomes for packaged seafood products.

Microbe(s): Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus, Campylobacter jejuni

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The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hyrol possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish.

Microbe(s): Vibrio parahaemolyticus

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Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products.

Microbe(s): Listeria monocytogenes

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Listeria monocytogenes contamination in ready-to-eat (RTE) fish products, in particular in cold-smoked salmon is an important food safety concern. This study evaluated the antimicrobial activity of electrolyzed oxidizing (EO) water as a pretreatment method during the process of cold-smoked salmon to inactivate L. monocytogenes. In addition, the effect of EO water treatment on the sensory and textural quality of the final product was also evaluated. Raw Atlantic salmon (Salmo salar) fillets were inoculated with L. monocytogenes (with an approximately cell number of 6 105 CFU/g L. monocytogenes ATCC 19114) and treated with EO water at three different temperatures (20, 30, and 40 C) and at three different exposure time of 2, 6, and 10 min before the cold-smoking process. A combination of EO water and a mild temperature (40 C) had reduced L. monocytogenes populations by 2.85 log10 CFU/g. The sensory as evaluated by a consumer panel (N = 71) and texture, which was measured by texture analysis showed no significant changes between EO and mild temperature treated samples and the control.

Microbe(s): Vibrio parahaemolyticus

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The bactericidal effects of strongly acidic hypochlorous acid water (StAHA) and slightly acidic hypochlorous acid water (SlAHA) against Vibrio parahaemolyticus contaminated on surface of raw fish and shellfish were examined. V. parahaemolyticus contaminated with about 7.0 log CFU/g on the meat chunk of olive flounder (Paralichthys olivaceus), and yellow tail (Seriola quinqueradiata), and 4.0 log CFU/g on the shucked scallop (Patinopecten yessoensis) were not detected after washing with StAHA and SlAHA at a ratio of 30:1 on a sample weight basis. However, 1.0 log CFU/g of V. parahaemolyticus was survived on shucked oyster (Crassostrea gigas) under same treatment conditions. The bactericidal effects of acidic hypochlorous acid water against V. parahaemolyticus contaminated on surface of shucked oyster were not as effective as those against V. parahaemolyticus contaminated on surface of meat chunk of olive flounder, yellow tail, and shucked scallop. Such differences can be attributed to the complicated surface conformation of oyster.

Microbe(s): MNV-1, Norovirus, HAV, Hepatitis A

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The ability of acidic electrolyzed oxidizing water (AEO) and neutral electrolyzed oxidizing water (NEO) to inactivate the murine norovirus (MNV-1) surrogate for human norovirus and hepatitis A virus (HAV) in suspension and on stainless steel coupons in the presence of organic matter was investigated. Viruses containing tryptone (0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were mixed with AEO and NEO for 1 min. In addition, stainless steel coupons containing MNV-1 with or without organic matter were treated with AEO or NEO for 3, 5, and 10 min. AEO was proven effective and generally killed more MNV-1 and HAV in suspension than NEO. Depending on the EO water generator, free chlorine concentrations are required to inactivate MNV-1 and HAV by 3-log PFU/mL or greater ranged from 30 mg/L to 40 mg/L after a 1 min contact time. The virucidal effect increased with increasing free chlorine concentration and decreased with increasing tryptone concentration in suspension. Both AEO and NEO at 70100 mg/L of free chlorine concentration significantly reduced MNV-1 on coupons in the absence of organic matter. However, there was no significant difference between these two treatments in the presence of organic matter. In addition, the efficacy of these two EO waters on stainless steel coupons increased with the increasing treatment time. Results indicated that AEO and NEO can reduce MNV-1 and HAV in suspension. However, higher free chlorine concentrations and longer treatment times may be necessary to reduce viruses on contact surfaces or in the presence of organic matter.

Microbe(s): Escherichia coli, Vibrio parahaemolyticus

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The aim of this study was to determine the combined effects of slightly acidic electrolyzed water SAEW (pH range 5.06.5, oxidationreduction potential 6501000 mV, available chlorine concentration 1080 mg/L) containing 0, 15, and 30 ppm chlorine and 0, 50, and 100 min of ultrasound US (37 kHz, 380 W) using the central composite design (CCD) on the reductions of Escherichia coli and Vibrio parahaemolyticus (initial value, approximately 67 log10 colony forming unit (CFU) of E. coli or V. parahaemolyticus/g) and the sensory properties on freshly sliced shad (Konosirus punctatus), in comparison with SAEW or US alone. Another aim was to develop the response surface model for E. coli and V. parahaemolyticus in the shad treated with the combination of SAEW and US. Single treatments with SAEW (chlorine 15 ppm), SAEW (chlorine 30 ppm), or US for 50 min caused a much-less-than-1-log10 reduction in the number of both E. coli and V. parahaemolyticus in the shad. In contrast, the combination of SAEW (15 or 30 ppm chlorine) and US (50 or 100 min) caused >1-log10 reduction of E. coli numbers (1.041.86 log reduction) and V. parahaemolyticus (1.021.42 log reduction) in the shad. In addition, the sensory properties of the shad were not changed under the harshest conditions of the combination (SAEW with chlorine at 30 ppm and US for 100 min). Response surface models were developed for the population of E. coli (Y=6.153220.024732X 10.016486X 20.00015X 1 X 20.00024X 1 20.00007X 2 2) and V. parahaemolyticus (Y=5.676490.042598X 10.014013X 20.00003X 1 X 20.00006X 1 20.00062X 2 2 ), where Y is the bacterial population (log10 CFU), X 1 is ppm chlorine in SAEW, and X 2 is the duration of treatment (min) with US. The appropriateness of the models was verified by bias factor (B f 1.10 for E. coli, 1.03 for V. parahaemolyticus), accuracy factor (A f 1.11 for E. coli, 1.05 for V. parahaemolyticus), mean square error (MSE 0.0087 for E. coli, 0.0028 for V. parahaemolyticus), and coefficient of determination (R 2 0.976 for E. coli, 0.982 for V. parahaemolyticus). To produce a 1-log10 reduction of E. coli and V. parahaemolyticus, US treatment times for E. coli and V. parahaemolyticus were calculated within the maximum of 54 and 67 min, respectively, at chlorine 10 ppm in SAEW. SAEW chlorine concentrations (ppm) for E. coli and V. parahaemolyticus were calculated within the maximum of 38 and 41 ppm, respectively, at 20 min of US. Therefore, the resulting response surface models for E. coli and V. parahaemolyticus should be further validated on slices of other kinds of raw fish. Ultimately, the response surface quadratic polynomial equations may thus be used for predicting the combined treatments of SAEW and against E. coli and V. parahaemolyticus in raw fish production, processing, and distribution.

Microbe(s): Total Microbial Count

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The combined effect of weakly acidic electrolyzed water (WAEW) ice-glazing and modified atmosphere packaging (MAP) treatment on the quality of pacific white shrimp (Litopenaeus vannamei) during frozen storage was investigated in terms of microbiological activity, TVBN, TMA and TBARS content, texture, color and volatile flavor analysis. As a result, significantly (p < 0.05) higher inhibitor effects on total aerobes and Staphylococcus aureus were observed in WAEW ice-glazed shrimp packaged in 40% CO2 + 10% O2 + 50% N2 or in 30% CO2 + 20% O2 + 50% N2 than the water- and WAEW ice-glazed batches. Additionally, chemical analysis results showed that WAEW ice-glazing combined with MAP was highly effective in maintaining lower TVBN, TMA and TBARS values in frozen shrimp, perhaps due to the synergistic effect of antibacterial and antioxidant abilities. On the other hand, the texture, L*, and a* results also confirmed that this combined treatment effectively retarded the degradation of the physical structure of shrimp muscle and showed a positive effect on the stability of color during frozen storage. However, the presence of WAEW ice-glaze showed a negative effect on the volatile flavor of thawed shrimp due to the volatile chlorine and chlorine dioxide, but no significant effect in the cooked samples. Overall, the application of WAEW ice-glazing combined with MAP on peeled frozen shrimp is advisable to achieve better quality maintenance and extend the shelf-life of refrigerated products.

Microbe(s): Vibrio parahaemolyticus

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The objective of this study was to investigate the fate of Vibrio parahaemolyticus on shrimp after acidic electrolyzed water (AEW) treatment during storage. Shrimp, inoculated with a cocktail of four strains of V. parahaemolyticus, were stored at different temperatures (4 30 C) after AEW treatment. Experimental data were fitted to modified Gompertz and Log-linear models. The fate of V. parahaemolyticus was determined based on the growth and survival kinetics parameters (lag time, ; the maximum growth rate, max; the maximum growth concentration, D; the inactivation value, K) depending on the respective storage conditions. Moreover, real-time PCR was employed to study the population dynamics of this pathogen during the refrigeration temperature storage (10, 7, 4 C). The results showed that AEW treatment could markedly (p < 0.05) decrease the growth rate ( max) and extend the lag time ( ) during the post-treatment storage at 30, 25, 20 and 15 C, while it did not present a capability to lower the maximum growth concentration (D). AEW treatment increased the sensitivity of V. parahaemolyticus to refrigeration temperatures, indicated by a higher (p < 0.05) inactivation value (K) of V. parahaemolyticus, especially for 10 C storage. The results also revealed that AEW treatment could completely suppress the proliferation of V. parahaemolyticus in combination with refrigeration temperature. Based on above analysis, the present study demonstrates the potential of AEW in growth inhibition or death acceleration of V. parahaemolyticus on seafood, hence to greatly reduce the risk of illness caused by this pathogen during post-treatment storage.

Microbe(s): Total Microbial Count

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Electrolyzed water ice is a relatively new concept developed in food industry in recent years. The objective of this study was to investigate the effects of acidic electrolyzed water (AEW) ice, compared with tap water (TW) ice, on quality of shrimp (Litopenaeus vannamei) in dark condition. The chemical changes, microbiological changes and polyphenol oxidase (PPO) activity of shrimp stored in AEW ice or TW ice were measured periodically. The results showed that AEW ice significantly (p < 0.05) inhibited the changes of pH, the formation of total volatile basic nitrogen (TVBN), and the proliferation of total bacteria counts in shrimp. The diversity of bacterial flora in shrimp stored in AEW ice was greatly reduced according to the Shannon index and the average similarity coefficient based on PCR-DGGE method. Additionally, AEW ice could serve as a potential substance to inhibit PPO activity in shrimp. Based on above analysis, AEW ice is a valid post-harvest treatment for preserving the quality of seafood in dark condition.

Microbe(s): (Listeria monocytogenes, Vibrio parahaemolyticus

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The objective of this study was to evaluate physicochemical properties and bactericidal activities of acidic electrolyzed water (AEW) used or stored at different temperatures on shrimp. Three independent experiments were carried out. The first experiment was to evaluate the physicochemical properties and bactericidal activities of AEW used at three different temperatures (4, 20, 50 C) against food-borne pathogens (Listeria monocytogenes and Vibrio parahaemolyticus) contamination on cooked shrimp at 1 or 5 min; the second one was to monitor the bactericidal activity of AEW used at two temperatures (20, 50 C) against total aerobic bacteria on raw shrimp at 5 min by conventional plate count method and PCR DGGE method; the last one was to examine the physicochemical properties and bactericidal activities of AEW (AEW1, AEW2) stored at two temperatures ( 18, 25 C) for 30 d against total aerobic bacteria on raw shrimp at 2 min. Results showed that AEW used at 50 C showed the best bactericidal activity, leading to a log reduction of 3.11 for V. parahaemolyticus, 1.96 for L. monocytogenes and 1.44 for total aerobic bacteria at 5 min, respectively. Conventional plate count and PCR DGGE (denaturing gradient gel electrophoresis) study further suggested that the bactericidal activity of AEW used at 50 C was higher than at 20 C. The loss of bactericidal activity of AEW stored at 18 C was less than that of stored at 25 C, and the ORP and ACC decreased more slowly than those of stored at 25 C. However, the ORP and ACC of AEW used at 50 C showed a remarkably faster decrease than that of used at 20 C. We suggest using AEW at 50 C to enhance bactericidal activity and storing at 18 C to keep the content of ACC and the bactericidal activity.

Microbe(s): Vibrio parahaemolyticus

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The objective of this study was to investigate the efficacy of acidic electrolyzed water (AEW) against Vibrio parahaemolyticus on shrimp. The shrimp was initially inoculated with V. parahaemolyticus(7 8 log CFU/g), and treated with AEW (AEW1 containing 51 mg/L of chlorine or AEW2 containing 78 mg/L of chlorine) or organic acids (2% AA and 2%LA) for 1 min or 5 min under different treated conditions. The effect of AEW was better than that of organic acids, the number of survival V. parahaemolyticus cells on shrimp was reduced by 0.9 log CFU/g after treatment for 5 min with AEW without vibration, while 1.0 log CFU/g bacteria cells reduced with vibration. No significant difference (p > 0.05) was observed between AEW and organic acids in the bactericidal activity with or without vibration. The effective order of temperatures on bactericidal activities of AEW was 50 C > 20 C > 4 C, and a 3.1 log CFU/g reduction of V. parahaemolyticus cells on shrimp was detected with treatment of AEW at 50 C. Mild heat greatly enhanced efficacy of electrolyzed water against V. parahaemolyticus. Basic electrolyzed water (BEW) (50 C) pretreatment combined with AEW (50 C) treatment remarkably reduced bacterial cells by 5.4 log CFU/g on shrimp after treatment for 5 min. There was a significant change in physicochemical properties (pH, ORP, ACC) of AEW, after it was used to wash shrimp (P < 0.05). This study suggests that BEW (50 C) pretreatment followed by AEW (50 C) treatment could be a possible method to effectively control V. parahaemolyticus contamination on shrimp.

Microbe(s): Escherichia coli

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Electrolyzed seawater (ESW) is reportedly an effective disinfectant for aquaculture equipment becaof its simple mechanism and cost effectiveness. The potential of electrolyzed seawater for oyster depuration was studied using different experiments. The first was determination of chlorine tolerance of oysters. Second was effectiveness of ESW against Escherichia coli in artificially contaminated oysters and third was effectiveness of ESW against E. coli in naturally contaminated oysters from two culture farms. Tolerance of oysters for Chlorine was studied by scanning electron microscopy (SEM) and histological observation demonstrating that more than 0.5 mg/L of chlorine was toxic while 0.2 mg/L was safe for the oysters. Oysters artificially contaminated with E. coli (230 MPN/100 mL, 16.5 C for 15 h) were depurated for 6, 24, and 48 h using ESW and UV irradiated seawater. E. coli counts in artificially contaminated oysters decreased to below the detection limit (30 E. coli MPN/100 g) after depuration with ESW for 24 h or UV irradiated seawater for 6 h. In experiments on naturally contaminated oysters E. coli counts decreased to below detection limits after depuration with ESW for 24 h. From these results, electrolysis of seawater is a useful method for post harvest elimination of E. coli from oysters.

Microbe(s): Listeria monocytogenes

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All food processing surfaces are potential sites for biofilm formation of foodborne pathogens, which may result in increased virulence and better adaptation to survival in foods. This study was aimed to evaluate the effect of two antimicrobials, neutral electrolyzed water (NEW) and nisin, and their combination, on Listeria monocytogenes Scott A biofilms formed on glass and stainless steel surfaces. We also examined the effects of sub-lethal doses of NEW on listeriolysin O (LLO) activity from free and biofilm listerial cells. Coupons inoculated with L. monocytogenes cells were used to produce biofilms by incubation for four days at 37 C. An orthogonal experimental design with two replicates was used to test the effect of four factors on biofilm population. The factors were antimicrobial agents: NEW (65 ppm), nisin (6976 IU/per coupon), and their combination; temperature: 20 C and 37 C; contact time: 5, 10, 20 and 45 min; and type of material: glass or stainless steel. Antimicrobial compounds and exposure time significantly affected L. monocytogenes populations in biofilms from both surfaces. A bactericidal effect was shown by NEW on free listerial cells at 30 ppm for 0.5 min of exposure, regardless treatment temperature. Same effect was observed on listerial biofilms at 65 ppm or higher concentrations, after 10 min contact time. A sub-lethal concentration of NEW acting on listerial biofilms resulted in an increased LLO activity, while non-treated biofilms exhibited a reduced activity, but higher than that found for free cells. The use of NEW as a sanitizer may be effective in reducing bacterial contamination. In addition because of its safety, which would benefit the food industry and its environmental friendliness, NEW may be of significant use in the food industry.

Microbe(s): Pseudomonas aeruginosa, Enterococcus faecalis, Micrococcus luteus

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In the dairy industry, cleaning and disinfection of surfaces are important issues and development of innovative strategies may improve food safety. This study was aimed to optimize the combined effect of alkaline electrolyzed water (AEW) and neutral electrolyzed water (NEW) as s were significantly affected by surface roughness electropolished SSP required 10 min, 100 mg/L AEW at 30 C, whereas SSP without modification required 30 min, 300 mg/L AEW at 30 C. From confirmatory tests cells removed were 3.90 0.25 log CFU/cm2 for electropolished SSP, and 3.20 0.20 log CFU/cm2 for SSP without modification. NEW is non-corrosive, and can be advantageously used for environmentally friendly cleaning and disinfection processes.

Microbe(s): Escherichia coli, Staphylococcus epidermidis

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This study investigated residual bacteria and different food types left on tableware items after various washing and sanitization protocols. Escherichia coli K-12 and Staphylococcus epidermidis were inoculated into whole milk and soft cream cheese. The milk was used to contaminate regular drinking glasses and the cheese was used to contaminate plates and silverware. These tableware items were washed in manual (43 C) and mechanical (49 C) washers and sanitized with different sanitizers (24 C) for 5 s. Quaternary ammonium compound, sodium hypochlorite, peroxyacetic acid, neutral electrolyzed water (NEW), and a combination of citric acid with sodium dodecylbenzene sulfonate (acidic formulation) were used as the chemical sanitizers. Tap water was used as a control. Results showed that at least 5-log reductions in both bacterial numbers were achieved for all sanitizers in both types of washers, except for the control. With mechanical dishwashing, the NEW and acidic formulation treatments reduced bacterial populations by >6.9 and >6.0 log CFU per tableware item, respectively. With the manual operation, bacterial numbers were reduced by >5.4 and >6.0 log CFU per tableware item, respectively. This study revealed that NEW and the acidic formulation are as effective as the other chemical sanitizers for food contact surface sanitization in manual and mechanical ware washing.

Microbe(s): Listeria monocytogenes

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The effects of electrolyzed oxidizing (EO) water on reducing Listeria monocytogenes contamination on seafood processing surfaces were studied. Chips (5 5 cm2) of stainless steel sheet (SS), ceramic tile (CT), and floor tile (FT) with and without crabmeat residue on the surface were inoculated with L. monocytogenes and soaked in tap or EO water for 5 min. Viable cells of L. monocytogenes were detected on all chip surfaces with or without crabmeat residue after being held at room temperature for 1 h. Soaking contaminated chips in tap water resulted in small-degree reductions of the organism (0.40 0.66 log cfu/chip on clean surfaces and 0.78 1.33 log cfu/chip on dirty surfaces). Treatments of EO water significantly (p < 0.05) reduced L. monocytogenes on clean surfaces (3.73 log on SS, 4.24 log on CT, and 5.12 log on FT). Presence of crabmeat residue on chip surfaces reduced the effectiveness of EO water on inactivating Listeria cells. However, treatments of EO water also resulted in significant reductions of L. monocytogenes on dirty surfaces (2.33 log on SS and CT and 1.52 log on FT) when compared with tap water treatments. The antimicrobial activity of EO water was positively correlated with its chlorine content. High oxidation reduction potential (ORP) of EO water also contributed significantly to its antimicrobial activity against L. monocytogenes. EO water was more effective than chlorine water on inactivating L. monocytogenes on surfaces and could be used as a chlorine alternative for sanitation purpose. Application of EO water following a thorough cleaning process could greatly reduce L. monocytogenes contamination in seafood processing environments.

Microbe(s): Vibrio parahaemolyticus, Vibrio vulnificus

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Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 107 CFU/ml) and V. vulnificus (8.69 107 CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (>6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 104 and 106 most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and 8h of treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (>12 h) of oysters in EO water containing high levels of chlorine (>30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to6hto avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.

Microbe(s): Total Microbial Count

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Aims: To evaluate the efficacy of electrolysed NaCl solutions (EW) for disinfecting bacterial isolates from carp, and the potential application of EW to reducing the bacterial load in whole carp and carp fillets. Methods and Results: EW was produced by using a two-compartment batch-type electrolysed apparatus. Pure cultures (in vitro), whole carp (skin surface) and carp fillets were treated with EW to detect its antimicrobial effects. The anodic solution [EW (+)] completely inhibited growth of the isolates. Furthermore, dipping the fish samples in EW (+) reduced the mean total count of aerobic bacteria on the skin of whole carp and in fillets by 2 8 and 2 0 log10, respectively. The cathodic solution [EW ( )] also reduced growth of the isolates from carp by ca 1 0 log10. Moreover, the total counts of aerobic bacteria in whole carp (on the skin) and fillets were reduced by 1 28 and 0 82 log10, respectively. Conclusions: EW (+) has a strong bactericidal effect on bacteria isolated from carp. Significance and Impact of the Study: Treatment with EW (+) could extend the shelf life of these fish.

Microbe(s): Listeria monocytogenes

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The effects of electrolyzed oxidizing (EO) water on reducing Listeria monocytogenes contamination on seafood processing surfaces were studied. Chips (5 5 cm2) of stainless steel sheet (SS), ceramic tile (CT), and floor tile (FT) with and without crabmeat residue on the surface were inoculated with L. monocytogenes and soaked in tap or EO water for 5 min. Viable cells of L. monocytogenes were detected on all chip surfaces with or without crabmeat residue after being held at room temperature for 1 h. Soaking contaminated chips in tap water resulted in small-degree reductions of the organism (0.40 0.66 log cfu/chip on clean surfaces and 0.78 1.33 log cfu/chip on dirty surfaces). Treatments of EO water significantly (p < 0.05) reduced L. monocytogenes on clean surfaces (3.73 log on SS, 4.24 log on CT, and 5.12 log on FT). Presence of crabmeat residue on chip surfaces reduced the effectiveness of EO water on inactivating Listeria cells. However, treatments of EO water also resulted in significant reductions of L. monocytogenes on dirty surfaces (2.33 log on SS and CT and 1.52 log on FT) when compared with tap water treatments. The antimicrobial activity of EO water was positively correlated with its chlorine content. High oxidation reduction potential (ORP) of EO water also contributed significantly to its antimicrobial activity against L. monocytogenes. EO water was more effective than chlorine water on inactivating L. monocytogenes on surfaces and could be used as a chlorine alternative for sanitation purpose. Application of EO water following a thorough cleaning process could greatly reduce L. monocytogenes contamination in seafood processing environments.

Microbe(s): None

ABSTRACT – Full Text PDF

In this study, the anaerobic digestion of thermally hydrolyzed wasted sludge (THWS) with a high concentration of ammonia was carried out through combining with an ammonia stripping and an electrolyzed water system (EWS). The EWS produced acidic water (pH 23) at the anode and alkaline water (pH 1112) at the cathode with an electro-diaphragm between the electrodes that could be applied to ammonia stripping. The ammonia stripping efficiency was strongly dependent on the pH and aeration rate, and the ammonium ion removal rate followed pseudo-first-order kinetics. From the BMP test, the methane yield of THWS after ammonia stripping using the EWS was 2.8 times higher than that of the control process (raw THWS without ammonia stripping). Furthermore, both methane yield and ammonium removal efficiency were higher in this study than in previous studies. Since ammonia stripping with the EWS does not require any chemicals for pH control, no precipitated sludge is produced and anaerobic microorganisms are not inhibited by cations. Therefore, ammonia stripping using the EWS could be an effective method for digestion of wastewater with a high concentration of ammonium nitrogen.

Microbe(s): None

ABSTRACT – Full Text PDF

An electrolytic process based on chlorine generation was adopted to treat wastewater containing textile dyes. In situ production of hypochlorous acid was achieved in an undivided electrolytic cell. The cell contained a graphite rod as the anode and a stainless steel sheet as the cathode. The generated chlorine reacts with water leading to the formation of hypochlorous acid and hydrochloric acid. The resultant hypochlorous acid, being an oxidising agent, oxidises the organic components present in the textile wastewater. In this study, the colour in wastewater containing Procion Navy and Procion Red dyes, respectively, was completely removed after 40 min of electrolysis at a constant current density of 39 mA/cm2 (where the initial dye concentrations were 3700 and 3200 mg/l, respectively). In the case of the Procion Yellow and composite dyes, complete colour removal occurred after 50 min of electrolysis (with initial dye concentrations of 3500 mg/l). Even though colour removal occurred during the electrolysis process, it required up to 180 min of electrolysis to reduce the COD values for the four dyes (Procion Navy, Red, Yellow and the composite) from the initial levels of 4520, 4200, 4170 and 4283 mg/l to 70, 45, 39 and 52 mg/l, respectively. This clearly indicates that the process removes both colour and organic components present in textile wastewater.

Microbe(s): Viruses, Hepatitis B Virus, HIV

ABSTRACT – Full Text PDF

Electrolyzed products of sodium chloride solution were examined for their disinfection potential against hepatitis B virus (HBV) and human immunodeficiency virus (HIV) in vitro. Electrolysis of 0.05% NaCl in tap water was carried out for 45 min at room temperature using a 3 A electric current in separate wells installed with positive and negative electrodes. The electrolyzed products were obtained from the positive well. The oxidation reduction potential (ORP), pH and free chlorine content of the product were 1053 mV, pH 2.34 and 4.20 ppm, respectively. The products modified the antigenicity of the surface protein of HBV as well as the infectivity of HIV in time- and concentration-dependent manner. Although the inactivating potential was decreased by the addition of contaminating protein, recycling of the product or continuous addition of fresh product may restore the complete disinfection against bloodborne pathogens.

Microbe(s): None

ABSTRACT – Full Text PDF

Particulate matter (PM) concentrations are high in cage-free aviary hen houses due to accumulation of litter on the floor and hen activities. The of a spraying agent such as acidic electrolyzed water (AEW) to mitigate PM levels and disinfect houses has been reported, and high spray dosages will reduce PM to a low level. However, spraying a high dose of AEW may generate high levels of ammonia (NH3) due to an increase in litter moisture content (LMC). Lab-scale experiments were conducted to assess the effect of AEW spray dosage and pH on PM and NH3 emissions from the litter of aviary hen houses. Four dynamic emission chambers (DECs) located in an environmentally controlled room were used for the evaluation. Three spray dosages of 25, 50, and 75 mL kg-1 dry litter d-1 (equivalent to area application rates of 125, 250, and 375 mL m-2, respectively) and three pH values of 3, 5, and 7 at a free-chlorine concentration of 200 mg L-1 were tested. Spraying occurred within 10 min once a day for five consecutive days. A no-spray regimen was used as the control. The results showed that higher spray dosages of AEW led to lower PM emissions. In particular, spraying dosages of 25, 50, and 75 mL kg-1 dry litter d-1 reduced PM levels by (mean SD) 71% 3%, 81% 1%, and 89% 1%, respectively, immediately after spraying. The PM reductions were still significant 24 h after spraying, averaging 57% 4%, 71% 5%, and 83% 1%, respectively. There was no significant difference (p = 0.30 to 0.43) in reduction efficiency among the PM sizes (i.e., PM1, PM2.5, PM4, PM10, and total suspended particulates). For NH3 emissions, spraying 75 mL kg-1 dry litter d-1 generated 5 to 6 times greater NH3 emissions when compared to 25 mL kg-1 dry litter d-1 due to the difference in LMC (22.6% vs. 13.0%). Meanwhile, spraying AEW of pH 7 yielded 2 to 3 times higher NH3 emissions than AEW of pH 3 at the same dosage. Ammonia emissions of all spray treatments were found to be higher than that of the control, albeit no significant difference between the control and the 25 mL kg-1 dry litter d-1 dosage at pH 3 or pH 5 (p = 0.81 and 0.47, respectively). Pearson correlation coefficients between NH3 and spray dosage (0.82) and pH value (0.46) indicated that spray dosage is more linearly correlated to NH3 emissions than pH value (p < 0.05). The results suggest that a 25 mL kg-1 dry litter d-1 dosage at pH 3 is a prudent combination to control PM levels without causing undesired elevation in NH3 emissions in litter-based cage-free aviary hen houses. This lab-based finding provides the basis for field verification testing.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

Slightly acidic electrolyzed water (SAEW) spray has been considered as a novel approach for airborne bacteria reduction in animal housing. This study aimed to optimize the operating parameters of SAEW spray based on the size distribution of sprayed aerosols, the available chlorine travelling loss in sprayed aerosols, and the reduction efficiency of airborne culturable bacteria (CB). The optimized operating parameters were the nozzle orifice diameter and the spray pressure. The size distribution 50) 60-90 m) are recommended for SAEW spray in animal housing.

Microbe(s): Avian influenza

ABSTRACT – Full Text PDF

Hypochlorous acid (HOCl) solutions were evaluated for their virucidal ability against a low pathogenic avian influenza virus (AIV), H7N1. HOCl solutions containing 50, 100 and 200 ppm chlorine (pH 6) or their sprayed solutions (harvested in dishes placed at 1 or 30 cm distance between the spray nozzle and dish) were mixed with the virus with or without organic materials (5 fetal bovine serum: FBS). Under plain diluent conditions (without FBS), harvested solutions of HOCl after spraying could decrease the AIV titer by more than 1,000 times, to an undetectable level (< 2.5 log10TCID50/ml) within 5 sec, with the exception of the 50 ppm solution harvested after spraying at the distance of 30 cm. Under the dirty conditions (in the presence of 5 FBS), they lost their virucidal activity. When HOCl solutions were sprayed directly on the virus on rayon sheets for 10 sec, the solutions of 100 and 200 ppm could inactivate AIV immediately after spraying, while 50 ppm solution required at least 3 min of contact time. In the indirect spray form, after 10 sec of spraying, the lids of the dishes were opened to expose the virus on rayon sheets to HOCl. In this form, the 200 ppm solution inactivated AIV within 10 min of contact, while 50 and 100 ppm could not inactivate it. These data suggest that HOCl can be used in spray form to inactivate AIV at the farm level.

Microbe(s): Newcastle disease virus, Avian avulavirus

ABSTRACT – Full Text PDF

Existence of bioaerosol contaminants in farms and outbreaks of some infectious organisms with the ability of transmission by air increase the need for enhancement of biosecurity, especially for the application of aerosol disinfectants. Here we SAHW containing 50 ppm chlorine in the aqueous phase. These data suggest that SAHW containing 100 ppm chlorine can be used for aerosol disinfection of NDV in farms.

Microbe(s): Phytophthora parasitica var. nicotianae

ABSTRACT – Full Text PDF

The efficiency of slightly acidic electrolyzed water (SAEW with pH 5.06.5) and strong acidic electrolyzed water (StAEW with pH less than 3.0) on the inactivation of Phytophthora parasitica var. nicotianae growth in vitro was studied. The treatment conditions included inundating time (30, 60, 120 and 300 s), treatment interval (24, 48 and 72 h) and available chlorine concentration (ACC, 30, 60 and 90 mg/L) with either StAEW (pH 2.35) or SAEW (pH 6.06). The results showed that inundating time had no effect on the efficiency of SAEW for inactivation of pure P. parasitica var. nicotianae cultures (P > 0.05). The inhibition rate increased with increasing ACC and oxidation reduction potential (ORP) at the same pH and inundating time (P < 0.01) with electrolyzed water (EW). Although the pH of SAEW (pH 6.06) was much higher than that of StAEW (pH2.35), the inhibition rate of SAEW was similar to that of StAEW (P > 0.05) at ACCs of 60 and 90 mg/L. Moreover, the experiments confirmed that the optimal treatment interval was 48 h (P < 0.01). An inhibition rate of higher than 50% of P. parasitica var. nicotianae growth in vitro was achieved with SAEW (pH 6.06, ORP 922 mV and ACC of 90 mg/L) when inundating time was 30 s and treatment interval was 48 h. The findings of this study indicate that EW may be a promising disinfectant, which can achieve inactivation of P. parasitica var. nicotianae with added benefits of reduced health hazards and environmental pollution.

Microbe(s): Fusarium graminearum

ABSTRACT – Full Text PDF

Fusarium Head Blight (FHB), caused by a blend of Fusarium species, is a destructive fungal disease of wheat and other small grain cereals. FHB has become an important issue in food and feed industry. Moreover, the majority of FHB pathogens have the ability to synthesize a range of mycotoxins. Although several physical and chemical control measures can be taken to control these fungi in the field, research is needed to provide new techniques for control during storage and transport of cereals. Mounting evidence shows that electrolyzed oxidizing water (EOW) has antimicrobial activity and might be a useful alternative for conventional control measures. The objective of the present work, was to investigate the influence of EOW on outgrowth and germination of Fusarium spp. and deoxynivalenol (DON) production. Both an in vitro and in vivo approach were pursued. In a first approach, a screening of the main FHB causing species was conducted. Secondly, the effect of EOW on Fusarium graminearum and the effect on DON biosynthesis was investigated using a trichothecene knockout mutant. These experiments showed an increase in DON levels upon sub lethal amendments of EOW to F. graminearum spores. In addition, the reactive oxygen species H2O2 was shown to govern this induction. Finally, the work was validated on a laboratory scale via an in vivo assay using wheat grains in which the Fusarium outgrowth was measured. The present work demonstrates that EOW has potential to control Fusarium spp. in wheat grains during transport and storage although sub lethal concentrations can result in increased DON biosynthesis.

Microbe(s): Fusarium sp.

ABSTRACT – Full Text PDF

The effects of ultrasound (US) and electrolyzed oxidizing (EO) water on postharvest decay of pineapple cv. Phu Lae were investigated using Fusarium sp. isolated from pineapple fruits. The effect of EO water and US irradiation on in vitro growth inhibition of Fusarium sp. was studied. Spore suspensions were treated EO water with free chlorine at 100, 200 and 300 ppm and different frequencies of 108, 400, 700 KHz and 1 MHz US irradiation for 0, 10, 30 and 60 min and incubated at 27 C for 48 h The study showed that all treatments of EO water totally inhibited the spore germination of the fungus. Additionally, US irradiation of 1 MHz for 60 min was the most effective to suppress the spore germination when compared with the control. When the fruits inoculated with Fusarium sp. were washed in EO water at 100 ppm and US irradiation or combination of US and EO water significantly inhibited the decay incidence and prolonged the shelf life of the pineapple for 20 days. Treatments had no effect on fruit quality (weight loss percentage, total soluble solids, titratable acidity, pH, and ascorbic acid). The potential for EO water in combination with US in pineapple handling systems is high, due to marked synergistic effects against fungal decay of decrowned pineapple fruit during storage.

Microbe(s): aflatoxin

ABSTRACT – Full Text PDF

Acidic electrolyzed oxidizing water (AcEW) is prepared by electrolyzing electrolyte solution using an electrolysis apparatus with an ion-exchange membrane. AcEW has a pH < 3.0, a high oxidationreduction potential (ORP) >1000 mV and a high available chlorine concentration (ACC). In this research, the effectiveness of AcEW on decontamination of aflatoxin B1 (AFB1) from naturally contaminated peanuts was investigated. According to our results, after the contaminated peanuts were soaked with AcEW solution (the ratio of liquid to solid was 5:1 (v/m)) for 15 min at room temperature, the content of AFB1 in peanuts decreased from 34.80 g/kg to around 5 g/kg. That is, about 85% AFB1 was decontaminated from contaminated samples. Ambient temperature and soaking time could markedly influence the elimination rate of AFB1 in contaminated peanuts. The elimination of AFB1 was relatively high when the ambient temperature was 25 C or 45 C. And the contaminated peanuts soaked in AcEW for 15 min can effectively decontaminate AFB1. In addition, the nutrition of peanuts didnt significantly change after treatment including the appearance of color. We also found that high level of ACC is the primary factor in AFB1 elimination. Furthermore, ACC in the form of HClO is probably more efficient than ACC in the form of ClO on AFB1 elimination.

Microbe(s): Escherichia coli O157: H7

ABSTRACT – Full Text PDF

Electrolyzed oxidizing water is a relatively new concept that has been utilized in agriculture, livestock management, medical sterilization, and food sanitation. Electrolyzed oxidizing (EO) water generated by passing sodium chloride solution through an EO water generator was used to treat alfalfa seeds and sprouts inoculated with a five-strain cocktail of nalidixic acid resistant Escherichia coli O157:H7. EO water had a pH of 2.6, an oxidation reduction potential of 1150 mV and about 50 ppm free chlorine. The percentage reduction in bacterial load was determined for reaction times of 2, 4, 8, 16, 32, and 64 min. Mechanical agitation was done while treating the seeds at different time intervals to increase the effectiveness of the treatment. Since E. coli O157:H7 was released due to soaking during treatment, the initial counts on seeds and sprouts were determined by soaking the contaminated seeds/sprouts in 0.1% peptone water for a period equivalent to treatment time. The samples were then pummeled in 0.1% peptone water and spread plated on tryptic soy agar with 50 g/ml of nalidixic acid (TSAN). Results showed that there were reductions between 38.2% and 97.1% (0.22 1.56 log10 CFU/g) in the bacterial load of treated seeds. The reductions for sprouts were between 91.1% and 99.8% (1.05 2.72 log10 CFU/g). An increase in treatment time increased the percentage reduction of E. coli O157:H7. However, germination of the treated seeds reduced from 92% to 49% as amperage to make EO water and soaking time increased. EO water did not cause any visible damage to the sprouts.

Microbe(s): None

ABSTRACT – Full Text PDF

Degradation of the 3 pesticides (acephate, omethoate, and dimethyl dichloroviny phosphate [DDVP]) by electrolyzed water was investigated. These pesticides were commonly used as broad-spectrum insecticides in pest control and high-residual levels had been detected in vegetables. Our research showed that the electrolyzed oxidizing (EO) water (pH 2.3, available chlorine concentration:70 ppm, oxidation-reduction potential [ORP]: 1170 mV) and the electrolyzed reducing (ER) water (pH 11.6, ORP: -860 mV) can reduce the pesticide residues effectively. Pesticide residues on fresh spinach after 30 min of immersion in electrolyzed water reduced acephate by 74% (EO) and 86% (ER), omethoate by 62% (EO) and 75% (ER), DDVP by 59% (EO) and 46% (ER), respectively. The efficacy of using EO water or ER water was found to be better than that of using tap water or detergent (both were reduced by more than 25%). Besides spinach, the cabbage and leek polluted by DDVP were also investigated and the degradation efficacies were similar to the spinach. Moreover, we found that the residual level of pesticide residue decreased with prolonged immersion time. Using EO or ER water to wash the vegetables did not affect the contents of Vitamin C, which inferred that the applications of EO or ER water to wash the vegetables would not result in loss of nutrition.

Microbe(s): Multiple

ABSTRACT – Full Text PDF

Microbial control of postharvest diseases has been extensively studied and appears to be a viable technology. Food safety must be ensured at each postharvest processing step, including handling, washing of raw materials, cleaning of utensils and pipelines, and packaging. Several commercial products are available for this purpose. The time is ripe for developing new techniques and technologies. The use of electrolyzed water (EW) is the product of a new concept developed in Japan, which is now gaining popularity in other countries. Little is known about the principle behind its sterilizing effect, but it has been shown to have significant bactericidal and virucidal and moderate fungicidal properties. Some studies have been carried out in Japan, China, and the USA on the pre- and postharvest application of EW in the field of food processing. EW may be produced using common salt and an apparatus connected to a power source. As the size of the machine is quite small, the water can be manufactured on-site. Studies have been carried out on the use of EW as a sanitizer for fruits, utensils, and cutting boards. It can also be used as a fungicide during postharvest processing of fruits and vegetables, and as a sanitizer for washing the carcasses of meat and poultry. It is cost-effective and environment-friendly. The use of EW is an emerging technology with considerable potential.

Microbe(s): Botrytis cinerea, Monilinia fructicola

ABSTRACT – Full Text PDF

Near neutral (pH 6.36.5) electrolyzed oxidizing water (EO water) has been demonstrated to inactivate fungi in pure culture and to mitigate infection on fruit surfaces. One possible and as effective as a once per week captan/once per week EO treatment. The once per week captan/once per week EO treatment was significantly more effective (P 0.05) than the captan once per week treatment. Dip treatments of strawberries in near neutral EO solutions (50 and 100 ppm TRC pH 6.36.5) did not leave a chlorine residue on the fruit relative to a water dip. The results from this study suggest that near neutral EO solutions could be used to manage infection of B. cinerea on strawberry plants in the field and also as a disinfection solution for harvesting equipment, greenhouses, packing houses and in commercial facilities to prevent or manage infections of B. cinerea and M. fructicola.

Microbe(s): Fungi

ABSTRACT – Full Text PDF

Acidic electrolyzed oxidizing (EO) water, generated by electrolysis of a dilute salt solution, recently gained attention in the food industry as a nonthermal method for microbial inactivation. Our objective was to determine if EO water has potential to control foliar diseases in greenhouses. Test fungi suspended in distilled water were combined with EO water (1:9 water:EO water) for various time periods, the EO water was neutralized, and germination was assessed after 24 h. Germination of all 22 fungal species tested was significantly reduced or prevented by EO water. All relatively thin-walled species (e.g., Botrytis, Monilinia) were killed by incubation times of 30 s or less. Thicker-walled, pigmented fungi (e.g., Curvularia, Helminthosporium) required 2 min or longer for germination to be reduced significantly. Dilution of EO water with tap water at ratios of 1:4 and 1:9 (EO:tap water) decreased efficacy against Botrytis cinerea. The presence of Triton X-100 (all concentrations) and Tween 20 (1 and 10%) eliminated the activity of EO water against B. cinerea. EO water did not damage geranium leaf tissue and inhibited lesion development by B. cinerea when applied up to 24 h postinoculation. EO water has a wide fungicidal activity which could facilitate its use as a contact fungicide on aerial plant surfaces and for general sanitation in the greenhouse.

Microbe(s): Fungi

ABSTRACT – Full Text PDF

The fungicidal effectiveness of electrolyzed oxidizing (EO) water on peach [Prunus persica (L.) Batsch.] fruit was studied. Fruit were inoculated with a spore suspension of 5 105 conidia/mL of Monilinia fructicola [(G. Wint.) Honey] applied as a drop on wounded and nonwounded fruits, or by a uniform spray-mist on nonwounded fruits. Fruit were immersed in tap water at 26 C for 5 or 10 minutes (control), or treated with EO water varying in oxidation-reduction potential (ORP), pH, and free available chlorine (FAC). Following treatment, fruit were held at 20 C and 95% relative humidity for 10 days to simulate retail conditions. Disease incidence was determined as the percentage of fruits showing symptoms of the disease, while severity was expressed as lesion diameter. EO water did not control brown rot in wound-inoculated fruits, but reduced disease incidence and severity in nonwound-inoculated peach. Symptoms of brown rot were further delayed in fruit inoculated by a uniform-spray mist compared with the nonwounded-drop-inoculated peaches. Fruit treated with EO water held for 8 days at 2 C, 50% RH, did not develop brown rot, until they were transferred to 20 C, 95% RH. The lowest disease incidence and severity occurred in fruit immersed in EO water for up to 5 minutes. EO water having pH 4.0, ORP 1,100 mV, FAC 290 mg L-1 delayed the onset of brown rot to 7 days, i.e., about the period peach stays in the market from a packing house to consumer. No chlorine-induced phytotoxicity was observed on the treated fruit. This study revealed that EO water is an effective surface sanitizer, but only delayed disease development.

Microbe(s): Tilletia indica

ABSTRACT – Full Text PDF

Definitive identification of free teliospores of Tilletia indica, causal agent of Karnal bunt of wheat, requires polymerase chain reaction (PCR)-based diagnostic tests. Since direct PCR amplification from teliospores has not been reliable, teliospores first must be germinated in order to obtain adequate DNA. We have routinely surface-sterilized teliospores for 2 min with 0.4% (vol/vol) sodium hypochlorite (NaOCl) to stimulate germination and produce axenic cultures. However, we observed that some spores were killed even with a 2-min NaOCl treatment, the shortest feasible duration. Decreasing the NaOCl concentration in our study from 0.4% to 0.3 and 0.2%, respectively, increased teliospore germination, but treatment times longer than 2 min still progressively reduced the germination percentages. In testing alternative methods, we found acidic electrolyzed water (AEW), generated by electrolysis of a weak solution of sodium chloride, also surface-sterilized and increased the rate of T. indica teliospore germination. In a representative experiment comparing the two methods, NaOCl (0.4%) for 2 min and AEW for 30 min increased germination from 19% (control) to 41 and 54%, respectively, by 7 days after treatment. Because teliospores can be treated with AEW for up to 2 h with little, if any, loss of viability, compared with 1 to 2 min for NaOCl, treatment with AEW has certain advantages over NaOCl for surface sterilizing and increasing germination of teliospores of suspect T. indica.

Microbe(s): Fungi

ABSTRACT – Full Text PDF

Electrolytically generated chlorine was injected into citrus microirrigation systems. Propagules of Phytophthora nicotianae var. parasitica, P. citrophthora, Fusarium spp., algae, and slime-forming bacteria were killed. Nematodes were found to resist free-chlorine levels in water of up to 50 g ml-1. Microemitters delivering chlorinated water were less frequently blocked by bacterial and/or bacterial slime than those delivering unchlorinated water. Soil and root populations of Phytophthora and nematodes under citrus trees in the field were unaffected by chlorinated water. No chlorine-induced phytotoxicity was observed on field-grown plants(.)

Microbe(s): Murine Norovirus surrogate for Human Norovirus

ABSTRACT – Full Text PDF

The ECOLOXTECH 240 system was used to generate a 50 ppm electrolyzed water solution of hypochlorous acid at pH 8 (25% solution of HOCl). Ceramic tile which had been innoculated with Murine Norovirus was treated with the hypochlorous acid solution for a contact time of 1 minute resulting in a 4-log reduction of Murine Norovirus.

Microbe(s): None

ABSTRACT – Full Text PDF

Ammonia (NH3) emissions from animal feeding operations (AFOs) are the source of a number of environmental issues. Wet spray scrubbers using non-acidic solutions might be a new approach for NH3 mitigation from AFOs. A lab-scale spray scrubber was built to clean 0.024 m3 s-1 of an NH3/air mixture with an average NH3 concentration of 20 ppmv. Three variables including contact time, nozzle type, and scrubbing solution were investigated to evaluate their effects on the ammonia removal efficiency of the scrubber. The contact times were to 0.3, 0.6, and 0.9 s, which were achieved by changing the elevation of the spray nozzle. Two types of spray nozzles were studied. The nozzles had full-cone spray patterns with different spray angles and different the scrubbing solution.

Microbe(s): All

ABSTRACT – Full Text PDF

The safety of electrolyzed seawater was evaluated by measuring the production rate of organic halogen compounds and the occurrence of reverse mutations. Aquaculture feedwater and wastewater were collected from a fish-culturing facility, and available chlorine of approximately 1.0 mg/L was generated to ensure a disinfectant effect. More than 90% of the generated organic halogen compounds were bromoform. The amount of bromoform was far less than the reference values for drinking water standards in Japan and the U.S., provided that the electrolyzation was performed within the range of normal use. The reverse mutation assay of electrolyzed seawater showed no mutagenicity. Electrolyzed seawater with available chlorine at an adequate level for disinfection can be used safely and effectively in various aspects of aquaculture.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

Reducing airborne dust is an essential process for improving hen housing environment. Dust reduction effects of neutral electrolyzed water (pH 8.2) spray were investigated in a commercial tunnel-ventilated layer breeding house during production in northern China. A multipoint sampler was used to measure airborne dust concentration to study the dust reduction effects and distribution in the house. Compared with the control treatment (without spray), airborne dust level was reduced 34% in the 3 hr after spraying 216 mL m 2 neutral electrolyzed water in the breeding house. The dust concentration was significantly higher during the periods of feed distribution (1.13 0.13 mg m 3) and artificial insemination (0.72 0.13 mg m 3) compared with after spray (0.47 0.09 mg m 3) and during lights-off period (0.29 0.08 mg m 3) in the three consecutive testing days (P < 0.05). The experimental cage area was divided into four zones along the length of the house, with zone 1 nearest to the evaporative cooling pad and zone 4 nearest to the fans. The air temperature, relative humidity, airflow rate, and dust concentration were measured at the sampling points of the four zones in 3 consecutive days and mortality of the birds for the duration of a month were investigated. The results showed that the air temperature, airflow rate, dust concentration, and number of dead birds increase from zone 1 to zone 4 in the tunnel-ventilated layer breeding house.

Microbe(s): Total Microbial Count

ABSTRACT – Full Text PDF

Hospitals are faced with increasingly resistant strains of micro-organisms. When it comes to disinfection, individual parts of electronic equipment of angiology diagnostics such as patient couches of computer tomography (CT) and magnetic resonance imaging (MRI) scanners prove to be very hard to disinfect. Disinfectants of choice are therefore expected to possess properties such as rapid, residue-free action without any damaging effect on the sensitive electronic equipment. This paper discusses the of the neutral electrolyzed oxidizing water (EOW) as a biocide for the disinfection of diagnostic rooms and equipment.MethodsThe CT and MRI rooms were aerosolized with EOW using aerosolization device. The presence of micro-organisms before and after the aerosolization was recorded with the help of sedimentation and cyclone air sampling. Total body count (TBC) was evaluated in absolute and log values.ResultsThe number of micro-organisms in hospital rooms was low as expected. Nevertheless, a possible TBC reduction between 78.9992.50% or 50.5070.60% in log values was recorded.ConclusionsThe research has shown that the of EOW for the air and hard surface disinfection can considerably reduce the presence of micro-organisms and consequently the possibility of hospital infections. It has also demonstrated that the sedimentation procedure is insufficient for the TBC determination. The of Biocide aerosolization proved to be efficient and safe in all applied ways. Also, no eventual damage to exposed devices or staff was recorded.

Microbe(s): Staphlycoccus Aureus

ABSTRACT – Full Text PDF

Electrolyzed strong and weak acid waters have been widely used for sterilization in clinical dentistry because of their excellent bactericidal activities. Electrolyzed neutral water was recently developed with a new concept of long-term good durability in addition to the excellent bactericidal activity similar to acid waters. The present study, evaluated the storage life of this water compared with the acid waters in terms of the changes in pH, oxidation-reduction potential (ORP), residual chlorine and bactericidal activity under several conditions using Staphylococcus aureus 209P. The strong acid water showed a rapid deterioration of its bactericidal activity. The weak acid and neutral waters exhibited excellent durability. Although all the bacteria were annihilated by the contact with the waters even stored for 40 days in the uncapped bottle, the neutral water was superior in further long-term duration.

Microbe(s): Staphylococcus aureus

ABSTRACT – Full Text PDF

Staphylococcus aureus is a major pathogen. It can form biofilm on the surfaces of medical devices and food equipment, which makes it more difficult to eradicate. To develop a novel method to eradicate S. aureus biofilm, the effects of electrolyzed water on removing and killing S. aureus biofilm were investigated in this study. By using a biofilm biomass assay with safranin staining and visualization of biofilm architecture with scanning electron microscopy, it was shown that basic electrolyzed water (BEW) could effectively remove established biofilm. The pH of electrolyzed water affected removal efficacy. Using a biofilm viability assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide staining, acidic electrolyzed water (AEW) efficiently killed biofilm-imbedded S. aureus. The available chlorine in AEW may be a main contributing factor for bactericidal activity. Additionally, BEW had a removal efficacy for S. aureus biofilm equivalent to 2% NaOH, and AEW had a bactericidal capability for S. aureus in biofilm equivalent to 2% HCl. These data suggested that AEW and BEW could be applied as a bactericide and removing agent for S. aureus in biofilm, respectively.

Microbe(s): Methicillin-resistant Staphylococcus aureus, MRSA

ABSTRACT – Full Text PDF

OBJECTIVE: Biofilms represent a key challenge in the treatment of chronic wounds, as they are among the main reasons for delays in chronic wound healing. This in vitro study was aimed at evaluating the activity of a new acid-oxidizing solution (AOS) on biofilm formation. Acid-oxidizing solution contains free chlorine species with stabilized hypochlorous acid in high concentration (> 95) and is RP2). Different approaches were used to assess the prevention and eradication of methicillin-resistant Staphyloccocus aureus biofilm by the study products. Xylitol and chlorhexidine were used as positive controls. The activity of the study products on the biofilm structure was evaluated analyzing the ultrastructural modification by scanning electron microscopy, while skin compatibility was assessed on noncolonized tissues measuring the metabolic activity of the cells. RESULTS: In all experiments, AOS showed to be active on the biofilm matrix, modifying its structure and allowing bacterial release from the matrix. In all experiments, no cytotoxicity was observed in the tissues treated with the product suggesting a good compatibility of AOS with skin tissues. Reference product 1 affected the biofilm, suggesting a disruption effect RP2 was slightly less active than AOS in modifying the biofilm structure. CONCLUSION: Treatment with AOS affects biofilm by modifying its structure and therefore facilitating local bacteria accessibility to bactericidal agents, with consequent potential clinical benefits in the treatment of chronic wounds.

Microbe(s): Viruses, HIV

ABSTRACT – Full Text PDF

Electrolyzed products of a sodium chloride solution contain free residual chlorine and have been proved to be effective for disinfection. Electrolyzed strong acid water containing a low sodium chloride concentration (ESW-L) is prepared by the electrolysis of a solution containing a low sodium chloride concentration (0.1% or less). Although ESW-L has been confirmed to be an effective disinfectant, disinfective efficacy against dried HIV-1 and a target of ESW-L against HIV-1 have not been clarified. In this study, we attempted to demonstrate the efficacy of ESW-L against dried HIV-1 which relatively resists disinfection and to analyze disinfection target. We demonstrated that ESWL inactivated the infectivity of dried HIV-1. In the analysis of the mechanism of disinfection, although the HIV-1 structural protein, p24 within the virus particle, was not inactivated by ESW-L, the enzymatic activity of reverse transcriptase (RT) and genomic RNA within the particle, however, were inactivated after the treatment with ESW-L. These findings suggest that the enzymatic activity of RT and genomic RNA are the target of ESW-L.

Microbe(s): Viruses, Hepadnavirus

ABSTRACT – Full Text PDF

Glutaraldehyde is used as a disinfectant for endoscopes, but is an irritant and so should be replaced by an alternative. Electrolysed acid water (EAW) has a bactericidal effect, and an endoscopic washing device using EAW has been developed in Japan. To investigate the effect of EAW on the infectivity of viruses, we treated duck hepatitis B virus (DHBV), which has similar properties to hepatitis B virus, with EAW, and determined the number of remaining infectious virus particles in a bioassay system. One-day-old Pekin ducks were inoculated with duck serum containing 105.5 ID50 DHBV; the serum had previously been incubated with 100 volumes of EAW or ion-exchanged water at room temperature for 7 min. DHBV infection was indicated by detection of viral DNA in duck serum samples 1 8 weeks after inoculation. Treatment of serum with EAW diminished DHBV infectivity whereas treatment with ion-exchanged water did not. The virus load was estimated to have been reduced to 101 103 ID50 during the first 1 min and to <100.5 ID50 in the next 6 min of incubation when compared with the control. Thus, EAW directly inactivates DHBV and its clinical application is recommended.

Microbe(s): Streptomyces spp

ABSTRACT – Full Text PDF

An acidic solution (pH 2.5 2.6) with a high oxidation-reduction potential (ORP; about +1,170 mV) and an alkaline solution (pH 11.5 11.7) with a low ORP (about 880mV) that resulted from electrolysis of 20 mM NaCl (dissolved in a pure water) were tested for their effect on the growth of Streptomyces spp. When spores ( 2 107) were exposed to the electrolyzed solutions (2 ml) for 1 minute, colony formation was totally inhibited by the acidic solution, but little by the alkaline solution although extending the exposure (10 minutes) resulted in a marked inhibition. The 1 minute exposure to their mixture (1:1, v/v) showed a strong inhibition (but weaker than that of the acidic solution). When the unexposed spores were streaked and incubated on ISP No. 4 (inorganic salts – starch medium) agar plate containing a cross density gradient of the acidic and alkaline solutions, a biased growth inhibition toward the acidic solution side was observed although the pH range of the acidic solution end of the plate was around 6.2. It seemed thus unlikely that low pH value contributed to the antimicrobial activity of the acidic solution. It was notable that S. griseus SS-1198 formed a unique morphology on the cross gradient plate. In addition, clear growth inhibition by the acidic solution was observed without direct contact with spores, probably because of chlorine gas release. Acidic solutions (pH 2.6 2.7) resulting from the electrolysis of 20 mM of Na2SO4 show no significant antimicrobial activity when tested by the cross gradient plate method. It thus seemed likely that chlorine played a key role for the antimicrobial activity of the acidic electrolyzed NaCl solution.

Microbe(s): Bacillus subtilis spores, Bacillus cereus spores

ABSTRACT – Full Text PDF

Spores of some Bacillus species are responsible for food spoilage and foodborne disease. These spores are highly resistant to various interventions and cooking processes. In this study, the sporicidal efficacy of acidic electrolyzed oxidizing (EO) water (AEW) and slightly acidic EO water (SAEW) with available chlorine concentration (ACC) of 40, 60, 80, 100, and 120 mg/L and treatment time for 1, 2, 3, 4, 5, and 6 min were tested on Bacillus subtilis and Bacillus cereus spores in suspension and on carrier with or without organics. The reduction of spore significantly increased with increasing ACC and treatment time (P < 0.05). Nondetectable level of B. cereus spore in suspension occurred within 2 min after exposure to both EO waters containing 120 mg/L ACC, while only SAEW at 120 mg/L and 2 min treatment achieved >6 log reductions of B. subtilis spore. Both types of EO water with ACC of 60 mg/L and 6 min treatment achieved a reduction of B. subtilis and B. cereus spores to nondetectable level. EO water with ACC of 80 mg/L and treatment time of 3 min on carrier test without organics addition resulted in reductions of B. subtilis spore to nondetectable level. But, addition of 0.3 organics on carrier decreased the inactivation effect of EO water. This study indicated that EO water was highly effective in inactivation of B. subtilis and B. cereus spores in suspension or on carrier, and therefore, rendered it as a promising disinfectant to be applied in food industry.

Microbe(s): Bacillus subtilis, Escherichia coli O157: H7

ABSTRACT – Full Text PDF

This study discussed the effects of different bacterial concentrations and centrifugations on the antimicrobial efficacy of electrolyzed oxidizing (EO) water on Bacillus subtilis and Escherichia coli O157:H7. Overnight grown bacterial cultures were centrifuged 1 to 3 times and bacterial concentrations were adjusted to approximately 9 (high), 7 (medium), or 5 (low) log10 CFU/mL. Antimicrobial efficacy of acidic EO water (AEW) and neutral pH EO water (NEW) containing 0.2530 mg/L available chlorine was determined. In order to ascertain the effects of AEW and NEW on targeted pathogens, cellular properties at bio-molecular levels were also studied. The results showed that the susceptibility of both pathogens decreased significantly with increasing bacterial concentrations. AEW with 10, 0.25 and 0.25 mg/L and NEW with 30, 0.5 and 0.25 mg/L available chlorine were needed for high, medium and low bacterial concentrations, respectively to non-detectable levels by direct plating for E. coli O157:H7. B. subtilis was found more resistant to both EO water treatments and only 4.1 and 3.8 log reductions were achieved for AEW and NEW containing 30 mg/L available chlorine. On the other hand, it was observed that as centrifugation time increased, both bacteria became significantly more sensitive to EO water treatments. When centrifugation period increased from 1 to 3 times, additional 2.67 and 3.38 log E. coli O157:H7 reductions were observed for AEW and NEW treatments, respectively. A similar trend was observed for B. subtilis. DNA and protein leakage increased when pathogens were treated by AEW and NEW with increasing available chlorine concentration, but decreased DNA and protein leakage were observed with increased centrifugation times. These results indicate that initial bacterial concentration and the centrifugation time are two important factors and should be carefully considered in chlorine-based antimicrobial efficacy testing.

Microbe(s): Staphylococcus aureus, Bacillus cereus, Escherichia coli, Aspergillus fumigatus

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Application of slightly acidic electrolyzed water (SAEW) in combination with ultrasound for decontamination of kashk was investigated. SAEW had a pH of 5.3-5.5, an oxidation reduction potential of 545-600 mV, and an available chlorine concentration of 20-22 mg/L. Kashk is a dairy product with a unique aroma and a high nutritive value produced in Iran. A 2/1 SAEW/kashk ratio showed 1.42, 1.13, 1.24, and 1.37 log CFU/mL microbial reductions in Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Aspergillus fumigatus, respectively, at room temperature. A combination of SAEW treatment with ultrasound (SAEWultrasound) resulted in 1.87, 1.67, 1.71, and 1.91 log CFU/mL reductions in S. aureus, B. cereus, E. coli, and A. fumigatus, respectively. The developed hurdle approach can be a useful tool for sanitization of kashk and similar products. Application of SAEWultrasound in dairy microbial decontamination is first reported herein.

Microbe(s): Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Myroides spp, MRSA, VRE

ABSTRACT – Full Text PDF

The aim of this study was to investigate the in-vitro antimicrobial activity of usage and normal concentrations of electrolyzed water in hospital. In our study, the effects of different concentrations of electrolyzed water on two gram positive, four gram negative standard strains and clinical isolates of four gram negative, two gram positive, one spore-forming bacillus and Myroides spp strains that lead to hospital infections were researched. The effects of different concentrations and different contact times of Envirolyte electrolyzed water on cited strains were researched through method of qualitative suspension tests. Petri dishes fo bacteria have been incubated at 37 C 48 hours. Bactericidal disinfectant was interpreted to be effective at the end of the period due to the lack of growth. Solutions to which disinfectant were not added were prepared with an eye to control reproduction and controlcultures were made by using neutralizing agents. 1/1, 1/2, and 1/10 concentrations of Envirolyte electrolyzed water were found to be effective on the bacteria that lead to hospital infections used during all test times. As a conclusion, based upon the results we acquired, it was observed that Envirolyte electrolyzed water of 100 concentration would be convenient to be used for disinfection when diluted to a usage concentration of 1/10.

Microbe(s): Fungi, Bacillus subtilis

ABSTRACT – Full Text PDF

A study was carried out on the disinfection efficiency of electrolyzed oxidizing water (EOW) on spores of Bacillus subtilis var. niger. The results showed a remarkable fungicidal rate of 100% after 20 min duration of 191 mg/L active available chlorine (ACC). The disinfection effect was improved with increased ACC or prolonged disinfection time, while organic interferents exerted a strong concentration-dependent inhibition against the disinfection. The disinfection mechanism was also investigated at bio-molecular level. EOW decreased dehydrogenase activity, intensified membrane permeability, elevated suspension conductivity, and caused leakage of intracellular K+, proteins, and DNA, indicating a damage of cell walls and membranes. Effects of EOW on microbiological ultra-structures were also verified by transmission electronic microscopy (TEM) images, showing that EOW destroyed protective barriers of the microbe and imposed some damages upon the nucleus area.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes, Bacillus cereus

ABSTRACT – Full Text PDF

This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.

Microbe(s): Bacillus spores, Candida, Acinetobacter, Shigella, Serratia, Proteus, Pseudomonas, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium abscessus, MRSA, VRSE

ABSTRACT – Full Text PDF

Background : Disinfection is essential for the prevention of hospital infection. Medilox, an super oxidized water generated by Medilox (SOO SAN EC CO., LTD. Yongin, Korea) was developed as a disinfectant in Korea. This is not costly and does not caany clinical problems and environmental pollution. We evaluated bactericidal activity ofMedilox against several clinical isolates and standard strains. Method : Clinical isolates and reference ATCC strains were exposed to Medilox, an super oxidized water (80 ppm ofHOCl) generated by Medilox (SOO SAN ECCO., LTD. Yongin, Korea) for the various periods (0.5, 1, 2, 5, and 10 minutes). After the exposure mixture of microorganisms and Medilox solution was inoculated into tryptic soy broth and onto tryptic soy agar, Sabouraud dextrose agar or Ogawa medium and cultured at 35C. Results: All strains of bacteria, yeasts, mycobacteria and vegetative form of Bacillus subtilis were killed within 30 seconds after an exposure to Medilox (80 ppm ofHOCl) under clean and dirty conditions. But, spore form of Bacillus subtilis was killed within 5 minutes. Conclusion: It may be recommended that Medilox can be used for the effective disinfectant for hospital environments and high-level disinfectant for hospital infection control.

Microbe(s): Bacillus cereus

ABSTRACT – Full Text PDF

The combined effects of ultrasonication and slight acidic electrolyzed water were investigated to improve the microbial safety of brown rice against Bacillus cereus infection and to evaluate the growth kinetics of these bacteria during storage of untreated and treated rice at various temperatures (5, 10, 15, 20, 25, 30, and 35C). The results indicate that this combination treatment was bactericidal against B. cereus, resulting in an approximately 3.29-log reduction. Although B. cereus can be efficiently reduced by treatment, temperature abduring storage can allow B. cereus to recover and grow. A primary growth model (Baranyi and Roberts equation) was fitted to the raw growth data from untreated (control) and treated samples to estimate growth rate, lag time, and maximum population density, with a low standard error of the residuals (0.140) and high adjusted coefficient of determination (>0.990). The growth curves obtained from the Baranyi and Roberts model indicated that B. cereus grew more slowly on treated brown rice than on untreated brown rice. Secondary models predicting the square root of the maximum growth rate and the natural logarithm of the lag time as a function of temperature were satisfactory (bias factor = 0.993 to 1.013 accuracy factor = 1.290 to 1.352 standard error of prediction = 18.828 to 36.615%). Inactivation results and the model developed and validated in this study provided reliable and valuable growth kinetics information for quantitative microbiological risk assessment studies of B. cereus on brown rice.

Microbe(s): Bacillus cereus

ABSTRACT – Full Text PDF

The effects of acidic electrolyzed water (AcEW), alkaline electrolyzed water (AlEW), 100 ppm sodium hypochlorite (NaClO), and 1% citric acid (CA) alone, and combinations of AcEW with 1% CA (AcEW + CA) and AlEW with 1% CA (AlEW + CA) against Bacillus cereus vegetative cells and spores was evaluated as a function of temperature (25, 30, 40, 50, or 60 C) and dipping time (3 or 6 h). A 3-strain cocktail of Bacillus cereus cells or spores of approximately 107 CFU/g was inoculated in various cereal grains (brown rice, Job s tear rice, glutinous rice, and barley rice). B. cereus vegetative cells and spores were more rapidly inactivated at 40 C than at 25 C. Regardless of the dipping time, all treatments reduced the numbers of B. cereus vegetative cells and spore by more than 1 log CFU/g, except the deionized water (DIW), which showed approximately 0.7 log reduction. The reductions of B. cereus cells increased with increasing dipping temperature (25 to 60 C). B. cereus vegetative cells were much more sensitive to the combined treatments than spores. The effectiveness of the combined electrolyzed water (EW) and 1% CA was considerable in inhibiting B. cereus on cereal grains. The application of combined EW and CA for controlling B. cereus cells and spores on cereal grains has not been previously reported. Therefore, the synergistic effect of EW and CA may provide a valuable insight on reducing foodborne pathogens on fruits, vegetables, and cereal grains.

Microbe(s): Escherichia coli, Bacillus subtilis

ABSTRACT – Full Text PDF

Acidic electrolyzed water (acidic EW), which is prepared by the electrolysis of an aqueous NaCl solution, has recently become of great importance for disinfection in a variety of fields, including medicine, the food industry and agriculture. In a previous paper we showed that: 1) acidic EW is a mixture of hypocholorite ion, hypochlorous acid and chlorine, depending upon the pH; 2) hypochlorous acid is primarily responsible for disinfection in the case of Escherichia coli K12 and Bacillus subtilis PCI219, both in clean culture media. In practice, however, the use of acidic EW is in many cases severely hampered due to the presence of a variety of non-selective reducing agents. In view of the salient nature of acidic EW, it is therefore strongly urged to establish an optimum way to use acidic EW in a variety of systems. The present paper is the first report on our attempt along this line in order to characterize the nature of the chemical changes that the bactericidal activity of the acidic EW deteriorates in the presence of organic materials, which include amino acids and proteins.

Microbe(s): Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, Morganella morganii, Proteus hauseri

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This study investigated efficacy of electrolyzed oxidizing water (EO water) and ice (EO ice) treatments in reducing histamine-producing bacteria (Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, Morganella morganii and Proteus hauseri) on food contact surfaces (ceramic tile and stainless steel) and fish skin (Atlantic salmon and yellowfin tuna). Soaking ceramic tile and stainless steel in EO water (50 ppm chlorine) for 5 min inactivated inoculated bacteria on the surface (>0.92 to >5.4 log CFU/cm2 reductions). E. cloacae, K. pneumoniae and P. hauseri did not survive well on fish skin. Soaking salmon skin in EO water (100 ppm chlorine) for 120 min resulted in 1.3 and 2.2 log CFU/cm2 reductions of E. aerogenes and M. morganii, respectively. A treatment of EO ice (100 ppm chlorine) for 24 h was capable of reducing E. aerogenes and M. morganii on tuna skin by 2.4 and 3.5 log CFU/cm2, respectively. EO water and EO ice can be used as post-harvest treatments for reducing histamine-producing bacteria on food contact surfaces and fish skin.

Microbe(s): Campylobacter

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This study investigated the effectiveness of spraying electrolysed water for reducing the numbers of Campylobacter on chicken carcasses. Previous studies have used solutions with free chlorine concentrations above 25 ppm and low pH to treat inoculated carcasses. The four trials described here were carried out at process plants treating naturally contaminated, hot, birds with electrolysed sodium chloride or sodium carbonate solutions, plain water, or no water. The birds were chilled after treatment. Free chlorine concentrations were all below 20 ppm, pH was 7 units or more, and redox potentials were below 830 mV. None of the treatments produced more than a 0.3-log reduction in Campylobacter numbers compared to counts on untreated carcasses. This study concludes that, at the low chlorine concentrations allowed in the EU, spraying with electrolysed water is not an effective method of reducing the number or prevalence of Campylobacter on chicken carcasses.

Microbe(s): Escherichia coli, Campylobacter, Salmonella

ABSTRACT – Full Text PDF

A study was conducted to investigate the effects of spray washing broiler carcasses with acidified electrolyzed oxidizing water (EO) or sodium hypochlorite (HOCl) solutions for 5, 10, or 15 s. Commercial broiler carcasses were contaminated with 0.1 g of broiler cecal contents inoculated with 105 cells of Campylobacter and 105 cells of nalidixic acid-resistant Salmonella. Numbers of bacteria recovered from unwashed control carcasses were 6.7, 5.9, 6.3, and 3.9 log10 cfu/mL for total aerobic bacteria, Escherichia coli, Campylobacter, and Salmonella, respectively. Washing in either EO (50 mg/L of sodium hypochlorite, pH 2.4, oxidation reduction potential of 1,180 mV) or HOCl (50 mg/L of sodium hypochlorite, pH 8.0) significantly reduced the levels of bacteria recovered from carcasses (P < 0.05). Carcasses washed with EO had slightly lower levels of total aerobic bacteria (0.3 log10 cfu/mL) and E. coli (0.2 log10 cfu/mL) than HOCl-treated carcasses; however, populations of Campylobacter and Salmonella were comparable after washing in either solution. Increasing the carcass washing time from 5 to 10 s lowered the levels of total aerobic bacteria (6.1 vs. 5.8 log10 cfu/mL), E. coli (4.6 vs. 4.1 log10 cfu/mL), Campylobacter (5.2 vs. 4.2 log10 cfu/mL), and Salmonella (2.0 vs. 1.2 log10 cfu/mL), but no further microbiological reductions occurred when washing time was extended from 10 to 15 s. Data from the present study show that washing poultry carcasses with EO is slightly better (total aerobic bacteria and E. coli) or equivalent to (Campylobacter and Salmonella) washing with HOCl. Washing broiler carcasses for a period equivalent to 2 inside-outside bird washers (10 s) provided greater reductions in carcass bacterial populations than periods simulating 1 (5 s) or 3 inside-outside bird washers (15 s).

Microbe(s): Campylobacter jejuni

ABSTRACT – Full Text PDF

This study was undertaken to investigate the efficacy of alkaline and acidic electrolyzed (EO) water in preventing and removing fecal contaminants and killing Campylobacter jejuni on poultry carcasses under simulated industrial processing conditions. New York dressed and defeathered chicken carcasses spot-inoculated with cecal material or C. jejuni were subjected to spraying treatment with alkaline EO or 10% trisodium phosphate (TSP) water or combinations of spraying and immersion treatments with acidic EO and chlorinated water, respectively. Prespraying chicken carcasses with alkaline EO water significantly lowered cecal material attachment scores (3.77) than tap water (4.07) and 10% TSP (4.08) upon treatment of the dorsal area. Combinations of pre- and postspraying were significantly more effective than postspraying only, especially when using alkaline EO water in removing fecal materials on the surface of chicken carcasses. Although treatment by immersion only in EO and chlorinated water significantly reduced the initial population (4.92 log10 cfu/g) of C. jejuni by 2.33 and 2.05 log10 cfu/g, respectively, combinations of spraying and immersion treatment did not improve the bactericidal effect of sanitizers. The results indicated that alkaline EO water might provide an alternative to TSP in preventing attachment and removal of feces on the surface of chicken carcasses. The results also suggested that chicken carcasses containing pathogenic microorganisms may contribute to the cross-contamination of whole batches of chickens during processing in the chiller tank and afterward.

Microbe(s): Campylobacter jejuni

ABSTRACT – Full Text PDF

The effectiveness of electrolyzed (EO) water for killing Campylobacter jejuni on poultry was evaluated. Complete inactivation of C. jejuni in pure culture occurred within 10 s after exposure to EO or chlorinated water, both of which contained 50 mg/l of residual chlorine. A strong bactericidal activity was also observed on the diluted EO water (containing 25 mg/l of residual chlorine) and the mean population of C. jejuni was reduced to less than 10 CFU/ml (detected only by enrichment for 48 h) after 10-s treatment. The diluted chlorine water (25 mg/l residual chlorine) was less effective than the diluted EO water for inactivation of C. jejuni. EO water was further evaluated for its effectiveness in reducing C. jejuni on chicken during washing. EO water treatment was equally effective as chlorinated water and both achieved reduction of C. jejuni by about 3 log10 CFU/g on chicken, whereas deionized water (control) treatment resulted in only 1 log10 CFU/g reduction. No viable cells of C. jejuni were recovered in EO and chlorinated water after washing treatment, whereas high populations of C. jejuni (4 log10 CFU/ml) were recovered in the wash solution after the control treatment. Our study demonstrated that EO water was very effective not only in reducing the populations of C. jejuni on chicken, but also could prevent cross-contamination of processing environments.

Microbe(s): Enterobacter aerogenes, Staphylococcus aureus

ABSTRACT – Full Text PDF

The effectiveness of electrolyzed (EO) water at killing Enterobacter aerogenes and Staphylococcus aureus in pure culture was evaluated. One milliliter (approximately 109 CFU/ml) of each bacterium was subjected to 9 ml of EO water or control water (EO water containing 10% neutralizing buffer) at room temperature for 30 s. Inactivation (reduction of >9 log10 CFU/ml) of both pathogens occurred within 30 s after exposure to EO water containing approximately 25 or 50 mg of residual chlorine per liter. The effectiveness of EO water in reducing E. aerogenes and S. aureus on different surfaces (glass, stainless steel, glazed ceramic tile, unglazed ceramic tile, and vitreous china) was also evaluated. After immersion of the tested surfaces in EO water for 5 min without agitation, populations of E. aerogenes and S. aureus were reduced by 2.2 to 2.4 log10 CFU/cm2 and by 1.7 to 1.9 log10 CFU/cm2, respectively, whereas washing with control water resulted in a reduction of only 0.1 to 0.3 log10 CFU/cm2. The washing of tested surfaces in EO water with agitation (50 rpm) reduced populations of viable cells on the tested surfaces to <1 CFU/cm2. For the control water treatment with agitation, the surviving numbers of both strains on the tested surfaces were approximately 3 log10 CFU/cm2. No viable cells of either strain were observed in the EO water after treatment, regardless of agitation. However, large populations of both pathogens were recovered from control wash solution after treatment.

Microbe(s): Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, MRSE, VRE Bacillus subtilis, Myroides spp.

ABSTRACT – Full Text PDF

Super-oxidized water is one of the broad spectrum disinfectants, which was introduced recently. There are many researches to find reliable chemicals which are effective, inexpensive, easy to obtain and use, and effective for disinfection of microorganisms leading hospital infections. Antimicrobial activity of super-oxidized water is promising. The aim of this study was to investigate the in-vitro antimicrobial activity of different concentrations of Medilox super-oxidized water that is approved by the Food and Drug Administration (FDA) as high level disinfectant. Material and methods In this study, super-oxidized water obtained from Medilox Soosan E & C, Korea device, which had been already installed in our hospital, was used. Antimicrobial activities of different concentrations of super-oxidized water (1/1, 1/2, 1/5, 1/10, 1/20, 1/50, 1/100) at different exposure times (1, 2, 5, 10, 30 min) against six ATCC strains, eight antibiotic resistant bacteria, yeasts and molds were evaluated using qualitative suspension test. Dey-Engley Neutralizing Broth Sigma-Aldrich, USA was used as neutralizing agent. Results Medilox was found to be effective against all standard strains (Acinetobacter baumannii 19606, Escherichia coli 25922, Enterococcus faecalis 29212, Klebsiella pneumoniae 254988, Pseudomonas aeruginosa 27853, Staphylococcus aureus 29213), all clinical isolates (Acinetobacter baumannii, Escherichia coli, vancomycin-resistant Enterococcus faecium, Klebsiella pneumoniae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Bacillus subtilis, Myroides spp.), and all yeastsat 1/1 dilution in 1 minute. It was found to be effective on Aspergillus flavus at 1/1 dilution in 2 minutes and on certain molds in 5 minutes. Conclusion Medilox super-oxidized water is a broad spectrum, on-site producible disinfectant, which is effective on bacteria and fungi and can be used for the control of nosocomial infection.

Microbe(s): Enterococcus faecium, Mycobacterium avium subspecies avium, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans

ABSTRACT – Full Text PDF

Standards of the German Association of Veterinary Medicine (DVG) for the evaluation of chemical disinfectants were used to assess the anti-microbial efficacy of electrolysed oxidizing water (EOW). Enterococcus faecium, Mycobacterium avium subspecies avium, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans were exposed to anode EOW (pH, 3.0 0.1; oxidation-reduction potential (ORP), +1100 50 mV; free chlorine, 400 20 mg/l Cl2) and combined EOW (7 : 3 anode : cathode, v/v; pH, 8.3 0.1; ORP, 930 950 mV; free chlorine, 271 20 mg/l Cl2). In water of standardized hardness (WSH), all bacterial strains were completely inactivated by a 30 min exposure to maximum 10.0% anode EOW ( 40.0 mg/l Cl2) or 50.0% combined EOW ( 135.5 mg/l Cl2). The sensitivity ranking order for anode EOW to the bacterial test strains was P. mirabilis > S. aureus > M. avium ssp. avium > E. faecium > P. aeruginosa. P. mirabilis and S. aureus decreased to undetectable levels after 5 min of exposure to 7.5% anode EOW ( 30.0 mg/l Cl2). Candida albicans was completely inactivated by a 5-min exposure to 5.0% anode EOW. Both, anode and combined EOW exhibited no anti-microbial activities in standardized nutrient broth or after addition of 20.0% bovine serum to the WSH. Further research is necessary to evaluate the efficacy of EOW as a disinfectant under operating conditions in animal production facilities.

Microbe(s): Enterococcus faecalis

ABSTRACT – Full Text PDF

Objective: The purpose of this study was to determine the antimicrobial efficacy of sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in human root canals infected by Enterococcus faecalis. Study design: One hundred sixty-five human single-rooted teeth were prepared and inoculated with E. faecalis for 48 h. Teeth were divided into 3 experimental groups according to the irrigation pattern used: group 1, 4.2% NaOCl pH 12; group 2, 4.2% NaOCl pH 7.5; and group 3, 4.2% NaOCl pH 6.5. Samples from the root canals were collected, and bacterial growth was analyzed by turbidity of the culture medium. Results: None of the irrigating solutions used in this study demonstrated 100% effectiveness against E. faecalis. The antibacterial effectiveness of 4.2% NaOCl at pH 6.5 was significantly increased (P = .03) compared with 4.2% NaOCl at pH 12 (chi-squared test: P < .05). Conclusion: Bactericidal activity of NaOCl solution is enhanced by weak acidification of 4.2% NaOCl solution at pH 6.5.

Microbe(s): Pseudomonas spp.

ABSTRACT – Full Text PDF

In the present study, we evaluated the antimicrobial activity of neutral electrolyzed water (NEW) against 14 strains of spoilage Pseudomonas of fresh cut vegetables under cold storage. The NEW, produced from solutions of potassium and sodium chloride, and sodium bicarbonate developed up to 4000 mg/L of free chlorine, depending on the salt and relative concentration used. The antimicrobial effect of the NEW was evaluated against different bacterial strains at 105 cells/ml, with different combinations of free chlorine concentration/contact time; all concentrations above 100 mg/L, regardless of the salt used, were found to be bactericidal already after 2 min. When catalogna chicory and lettuce leaves were dipped for 5 min in diluted NEW, microbial loads of mesophilic bacteria and Enterobacteriaceae were reduced on average of 1.7 log cfu/g. In addition, when lettuce leaves were dipped in a cellular suspension of the spoiler Pseudomonas chicorii I3C strain, diluted NEW was able to reduce Pseudomonas population of about 1.0 log cfu/g. Thanks to its high antimicrobial activity against spoilage microorganisms, and low cost of operation, the application of cycles of electrolysis to the washing water looks as an effective tool in controlling fresh cut vegetable microbial spoilage contamination occurring during washing steps.

Microbe(s): Penicillium digitatum, Pseudomonas spp.

ABSTRACT – Full Text PDF

The efficacy of thin-film diamond coated electrodes (DiaCell 101) for disinfection of water artificially contaminated with Penicillium digitatum and Pseudomonas spp. was tested. Electrolysis process was performed with different operation conditions: current densities at 4, 8, and 12A and water flow rate at 150, 300, and 600 L/h. For both pathogens, the experiments were performed in water suspensions at a final concentration of 105 CFU/ml. Tap water was used as a control. The results showed that fungal spores and bacterial cells were affected by flow rate and current density applied. The higher the water flow rate the greater the inactivation of the two microorganisms which were completely suppressed at high recirculation flow (300-600 L/h/cell). Pseudomonas spp. cells were inactivated at the highest current density applied (8-12A) after 6 min of electrolysis, whereas for P. digitatum the complete inactivation was observed at the same current densities after 12 min. The results obtained suggest that the two parameters can be modulated in order to achieve significant suppression in relation to the target microorganism and to obtain an antimicrobial effect without generation of chlorine.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

ABSTRACT – Full Text PDF

The effects of low-concentration electrolysed water (LcEW) (4 mg/L free available chlorine) combined with mild heat on the safety and quality of fresh organic broccoli (Brassica oleracea) were evaluated. Treatment with LcEW combined with mild heat (50 C) achieved the highest reduction in naturally occurring microorganisms and pathogens, including inoculated Escherichia coli O157:H7 and Listeria monocytogenes (P < 0.05). In terms of the antioxidant content of the treated broccoli, the total phenolic levels and ferric reducing antioxidant power remained unchanged however, the oxygen radical absorbance capacity of the treated broccoli was higher than that of the untreated control. In addition, mild heat treatment resulted in an increase in firmness. The increased firmness was attributed to changes in the pectin structure, including the assembly and dynamics of pectin. The results revealed that mild heat induced an antiparallel orientation and spontaneous aggregation of the pectin chains. This study demonstrated that LcEW combined with mild heat treatment was effective to reduce microbial counts on fresh organic broccoli without compromising the product quality.

Microbe(s): Escherichia coli ATCC 25922, Pichia pastoris GS115, Aureobasidium pullulans

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The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift ificantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.

Microbe(s): Escherichia coli

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Microbe(s):

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In the present study, the disinfection efficacy on fresh-cut cilantro of the combination of strongly acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW) was evaluated, in comparison with single slightly acidic electrolyzed water (SAEW) and single AcEW treatments. The populations of E. Coli O78 on inoculated cilantro treated by AlEW 5 min + AcEW 5 min, was not detected while 3.43 and 3.73 log10 CFU/g in the AlEW 2.5 min + AcEW 2.5 min and AcEW 2 min + AlEW 2 min + AcEW 2 min treatments respectively. Our results implied that the bactericidal abilities of the combination of AlEW and AcEW treatments were higher than that of single AcEW and SAEW, which also was demonstrated microscopically by scanning electron microscopy (SEM). Moreover, the efficacy of combination of AcEW and AlEW in reducing natural micro flora on fresh-cut cilantro was also evaluated compared with single AcEW and SAEW. The results showed that the combination of AlEW and AcEW had stronger sterilization ability than single AcEW and SAEW. Considering the utilizations of AlEW and disinfection efficacy, we suggest that the combination of AlEW and AcEW may also be a better choice in fresh-cut produce.

Microbe(s): Total Microbial Count, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas spp., Fungi, Yeast

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This study evaluated the efficacy of individual treatments (thermosonication [TS+DW] and slightly acidic electrolyzed water [SAcEW]) and their combination on reducing Escherichia coli O157:H7, Listeria monocytogenes, and spoilage microorganisms (total bacterial counts [TBC], Enterobacteriaceae, Pseudomonas spp., and yeast and mold counts [YMC]) on fresh-cut kale. For comparison, the antimicrobial efficacies of sodium chlorite (SC; 100 mg/L) and sodium hypochlorite (SH; 100 mg/L) were also evaluated. Each 10 g sample of kale leaves was inoculated to contain approximately 6 log CFU/g of E. coli O157:H7 or L. monocytogenes. Each inoculated or uninoculated samples was then dip treated with deionized water (DW; control), TS+DW, and SAcEW at various treatment conditions (temperature, physicochemical properties, and time) to assess the efficacy of each individual treatment. The efficacy of TS+DW or SAcEW was enhanced at 40 C for 3 min, with an acoustic energy density of 400 W/L for TS+DW and available chlorine concentration of 5 mg/L for SAcEW. At 40 C for 3 min, combined treatment of thermosonication 400 W/L and SAcEW 5 mg/L (TS+SAcEW) was more effective in reducing microorganisms compared to the individual treatments (SAcEW, SC, SH, and TS+DW) and combined treatments (TS+SC and TS+SH), which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, TBC, Enterobacteriaceae, Pseudomonas spp., and YMC by 3.32, 3.11, 3.97, 3.66, 3.62, and >3.24 log CFU/g, respectively. The results suggest that the combined treatment of TS+SAcEW has the potential as a decontamination process in fresh-cut industry.

Microbe(s): Listeria monocytogenes

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Time to detection experiments (TTD) based on turbidometry using an automatic Bioscreen C is a useful and straightforward method for estimating microbial growth parameters (lag time (), growth rate () and work to be done (h0)) at constant temperature. This study investigated the effects of slightly acidic electrolyzed water (SAEW) and heat treatment on Listeria monocytogenes growth at different recovery temperatures (10 C, 15 C, 25 C, and 30 C). Similar surviving and sublethally injured L. monocytogenes populations were obtained by heat treatment (55 C for 10 min) and SAEW treatment (available chlorine concentration of 30 mg/l and ratio of bacteria against SAEW of 8:2 for 30 s). In these experimental conditions, stresses had greater impact on the and h0 parameter in comparison with recovery temperature while there was no great change in growth rate under isothermal conditions. Larger values and h0 parameters were observed in sublethal-heat injured L. monocytogenes (the maximum and h0 parameters are 30.199 h and 1.6492) as compared to SAEW groups (the maximum and h0 parameters are 22.634 h and 1.4396). The sensitivity analysis of SAEW and heat treatments on h0 parameter indicated that SAEW treatment showed a higher influence. The collinearity diagnostics of independent variables recovery temperature (T), , for dependent variable (h0 parameter) demonstrated that T, and had strong collinearity. In addition, the established secondary models in this study have good performances on predicting the effect of recovery temperature on bacterial growth parameters.

Microbe(s): Listeria monocytogenes

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Listeria monocytogenes contamination in ready-to-eat (RTE) fish products, in particular in cold-smoked salmon is an important food safety concern. This study evaluated the antimicrobial activity of electrolyzed oxidizing (EO) water as a pretreatment method during the process of cold-smoked salmon to inactivate L. monocytogenes. In addition, the effect of EO water treatment on the sensory and textural quality of the final product was also evaluated. Raw Atlantic salmon (Salmo salar) fillets were inoculated with L. monocytogenes (with an approximately cell number of 6 105 CFU/g L. monocytogenes ATCC 19114) and treated with EO water at three different temperatures (20, 30, and 40 C) and at three different exposure time of 2, 6, and 10 min before the cold-smoking process. A combination of EO water and a mild temperature (40 C) had reduced L. monocytogenes populations by 2.85 log10 CFU/g. The sensory as evaluated by a consumer panel (N = 71) and texture, which was measured by texture analysis showed no significant changes between EO and mild temperature treated samples and the control.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The effects of hardness and pH of water used to prepare electrolyzed oxidizing (EO) water and bleach solutions on the bactericidal activity of sanitizer prepared from the water were examined. EO water and bleach solutions were prepared with hard water of 0, 50, 100, and 200 mg/l as CaCO3 at pH 5, 6, 7, and 8. Increased water hardness tended to increase free chlorine and oxidation-reduction potential (ORP) and decrease pH of EO water. Chlorine levels also increased with water pH. Water hardness and pH only had minor effect on the pH of bleach solutions. Increasing hardness to 50 mg/l increased antimicrobial effect of EO water against Escherichia coli O157:H7, but reduced when water hardness further increased to 100 mg/l or higher. Water pH had no effect on EO water produced against E. coli O157:H7. Water hardness had no significant effect on bactericidal activity of EO water against Listeria monocytogenes but elevated water pH decreased bactericidal activity of EO water produced against L. monocytogenes. Bleach solution prepared using hard water at 200 mg/l or at pH 7 or higher had significant lower efficacy in inactivating E. coli O157:H7, but had no effect on the inactivation of L. monocytogenes. Results indicate that increasing the hardness or pH of water used to prepare EO water or bleach solutions will decrease the bactericidal activity of sanitizers prepared from the water.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The objectives of this study were to evaluate the effectiveness of low concentration electrolyzed water (LcEW) and other carcass decontaminants against Escherichia coli O157:H7 and Listeria monocytogenes in fresh pork and to conduct the shelf life/sensory study of pork. Pork samples were inoculated with approximately 5 log cfu/g of afore mentioned pathogens and dip treated with distilled water (DW), aqueous ozone (AO), 3% lactic acid (LA), 3% calcium lactate (CaL), sodium hypochlorite solution (NaOCl), LcEW, strong acidic electrolyzed water (SAEW), and LcEW + CaL for 5 min at room temperature (23 2 C). The greatest reduction (3.0 3.2 log cfu/g) was achieved with LcEW + CaL against pathogens and significantly differed (p < 0.05) from other treatments. This combination also extended shelf life of pork up to 6 days at 4 C storage.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The objective of this study was to determine the synergistic effect of alkaline electrolyzed water and citric acid with mild heat against background and pathogenic microorganisms on carrots. Shredded carrots were inoculated with approximately 6 7 log CFU/g of Escherichia coli O157:H7 (932, and 933) and Listeria monocytogenes (ATCC 19116, and 19111) and then dip treated with alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaOCl), deionized water (DaIW), or 1% citric acid (CA) alone or with combinations of AlEW and 1% CA (AlEW + CA). The populations of spoilage bacteria on the carrots were investigated after various exposure times (1, 3, and 5 min) and treatment at different dipping temperatures (1, 20, 40, and 50 C) and then optimal condition (3 min at 50 C) was applied against foodborne pathogens on the carrots. When compared to the untreated control, treatment AcEW most effectively reduced the numbers of total bacteria, yeast and fungi, followed by AlEW and 100 ppm NaOCl. Exposure to all treatments for 3 min significantly reduced the numbers of total bacteria, yeast and fungi on the carrots. As the dipping temperature increased from 1 C to 50 C, the reductions of total bacteria, yeast and fungi increased significantly from 0.22 to 2.67 log CFU/g during the wash treatment (p 0.05). The combined 1% citric acid and AlEW treatment at 50 C showed a reduction of the total bacterial count and the yeast and fungi of around 3.7 log CFU/g, as well as effective reduction of L. monocytogenes (3.97 log CFU/g), and E. Coli O157:H7 (4 log CFU/g). Combinations of alkaline electrolyzed water and citric acid better maintained the sensory and microbial quality of the fresh-cut carrots and enhanced the overall shelf-life of the produce.

Microbe(s): Escherichia coli, Listeria innocua

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The effects of various sanitizers on the viability and cellular injury to structures of Escherichia coli and Listeria innocua were investigated. A food grade organic acidic formulation (pH 2.5) and acidic, neutral, and basic electrolyzed water [AEW (pH 2.7, oxidation reduction potential; ORP: 1100 mV, free available chlorine; FAC: 150 ppm), NEW (pH 6.9, ORP: 840 mV, FAC: 150 ppm), BEW (pH 11.6, ORP: 810 mV)] were used to treat E. coli and L. innocua cells. After 10 min of exposure to the sanitizers, changes to the bacterial numbers and cell structures were evaluated by plate counting and transmission electron microscopy (TEM), respectively. It was concluded from the results that the sanitizers reduced the E. coli cells between 2 and 3 log CFU/mL. Except for the BEW treatment, reductions in L. innocua population were greater (>1 log CFU/mL) than that of E. coli for all treatments. Data from the TEM showed that all sanitizers caused changes to the cell envelope and cytoplasm of both organisms. However, smaller changes were observed for L. innocua cells. Decrease in the integrity of the cell envelope and aggregation of the cytoplasmic components appeared to be mainly because of exposure to the sanitizers. The organic acid formulation and AEW were the most effective sanitizers against bacterial cells, indicating that penetration of acidic substances effectively caused the cell inactivation.

Microbe(s): Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes

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Electrochemically activated water (ECAW), also known as electrolyzed water, and ozonized water are typically effective in inactivating bacteria, but their generation typically uses high current and voltage. A few simpler antimicrobial technologies that are also based on the application of a mild electrical current have been recently marketed to food retail and service customers claiming to have sanitizing properties for controlling bacteria. The objective of this study was to determine the sanitizing effect of some of these commercial technologies on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica and compare them with sterile water, generated ECAW generated with a pilot size electrolyzing unit, and salt solutions sprayed using commercial device sprays. A concentration of 100 mg/L ECAW had sanitizing effects of at least 5 log CFU/mL reductions on liquid culture and more than 4 log CFU/coupon reductions for E. coli O157:H7, L. monocytogenes and Salmonella dried on stainless steel surface, respectively. No bacterial cells were detected by direct plate counting post-ECAW treatment. In contrast, the treatment of liquid cultures with any of the commercial technologies tested resulted in non-significant bacterial cell reductions greater than 0.5 log CFU/mL. Similarly, when cells had been dried on metal surfaces and treated with any of the water generated with those technologies, no reductions were observed. When the manufacturer s instructions were followed, the reduction of cells on surface was largely due to the physical removal by cloth-wiping after water fraction application. These results indicate that treatment with any of these portable technologies had no noticeable antimicrobial activity. These results would be helpful for guiding consumers when choosing a right sanitization to ensure food safety.

Microbe(s): Escherichia coli O157:H7

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The resistance of thirty two strains of Escherichia coli O157:H7 and six major serotypes of non-O157 shiga toxin-producing E. coli (STEC) plus E. coli O104:H4 was tested against electrolyzed oxidizing (EO) water using two different methods; modified AOAC 955.16 sequential inoculation method and minimum inhibitory concentration (MIC). In sequential inoculation method efficacy of sodium hypochlorite was also compared with equal free chlorine (45 mg/L) containing EO water. MIC experiments were conducted for 15 s testing period with free chlorine concentrations of 3.00, 2.50, 2.00, 1.50, 1.00, 0.50 and 0.25 mg/L. The individual strain resistance when tested using the sequential inoculation method was in between 5 and 10 positive tubes, where greater numbers of positive tubes indicate increased resistance of the respective strain to the particular sanitizer. The MIC of individual strains ranged from 0.50 to 1.50 mg/L free chlorine of EO water. In comparison to sodium hypochlorite at same free chlorine concentration EO water was more effective against all STEC cocktails tested. The resistance of STEC cocktails using sequential inoculation method was determined as E. coli O157 O103 O26 0111 O121 045 > O145. The similar pattern of resistance was observed when cocktails were subjected to MIC. The results indicate that different strains of same serotype can differ in their resistance toward an intervention. In addition, EO water treatment that reduces E. coli O157:H7 can equally if not more effectively reduce other non-O157 STEC tested.

Microbe(s): Escherichia coli O157:H7

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The effect of operating conditions (current density, recirculation flow rate and electrode doping level) on the efficacy of boron-doped diamond (BDD) electrodes to inactivate microorganisms and decrease chemical oxygen demand (COD) was studied in lettuce process wash water with a COD of 725 mg/L and inoculated with a 5-strain cocktail of Escherichia coli O157:H7. Changes in pathogen population, COD, pH, temperature, redox potential, and free and total chlorine were monitored in process wash water during treatments. Considering the specific characteristics of the washing step included in the fresh-cut processing, the disinfection of process wash water should be of fast action. A biphasic with a shoulder model was used to estimate shoulder length (Sl), log-linear inactivation rates (kmax1,kmax2), lowest population (Nf) and highest log reduction (HLR). Current density clearly influenced Sl, and kmax2; recirculation flow rate influenced Sl, kmax1,kmax2 and COD depletion; and doping level influenced Nf. No relationship was observed between inactivation parameters and chlorine concentration. Conditions including high current density (180 mA/cm2), high flow rate (750 l/h) and high doping level (8 000 mol/mol) seems to provide a disinfection efficiency suitable to decrease the chance of bacterial cross contamination in the fresh-cut industries while saving on water consumption and decreasing the amount of wastewater effluents.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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Slightly acidic electrolyzed water (SAEW) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. However, microbial reductions from SAEW treatment are not enough to ensure produce safety. Therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. This study examined the microbicidal activity of SAEW (pH 5.2-5.5, oxidation reduction potential 500-600 mV, available chlorine concentration 21-22 mg/l) on Chinese cabbage, lettuce, sesame leaf and spinach, four common fresh vegetables in Korea under same laboratory conditions. Subsequently, effects of ultrasonication and water wash to enhance the sanitizing efficacy of SAEW were studied, separately. Finally, an optimized simple and easy approach consisting of simultaneous SAEW treatment with ultrasonication (3 min) followed by water wash (150 rpm, 1 min) was developed (SAEW + US-WW). This newly developed hurdle treatment significantly enhanced the microbial reductions compared to SAEW treatment alone, SAEW treatment with ultrasonication (SAEW + US) and SAEW treatment followed by water wash (SAEW-WW) at room temperature (23 2 C). Microbial reductions of yeasts and molds, total bacteria count and inoculated Escherichia coli O157:H7 and Listeria monocytogenes were in the range of 1.76-2.8 log cfu/g on different samples using the new hurdle approach.

Microbe(s): Escherichia coli

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The food industry has recognized electrolyzed oxidizing water (EOW) as a promising alternative decontamination technique. However, there is not a consensus about the sanitizing mechanism of EOW. In this study, we evaluated the disinfection efficacy of different types of EOW on Escherichia coli. Based on the hypothesis of hydroxyl radicals existing in EOW, in the present study, the hydroxyl radicals existed in slightly acidic electrolyzed water (SAEW) and acidic electrolyzed water (AEW) diluted to different levels were detected quantitatively. An ultraviolet (UV) spectrophotometer was used to scan EOW with different pH values. Accounting for the results of UV scanning to EOW with different pH value and the disinfection efficacy of different types of EOW, it can be concluded that considering the lower chlorine concentration of EOW compared with traditional chlorine disinfectants, the existing form of chlorine compounds rather than the hydroxyl radicals played important role in the disinfection efficacy of EOW.

Microbe(s): Escherichia coli O157:H7

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The objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (SAEO) water in killing or removing Escherichia coli O157:H7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. Whole lettuce leaves and tomatoes were spot-inoculated with 100 L of a mixture of 5 strains of E. coli O157:H7. Washing lettuce with SAEO water for 15 s reduced the pathogen by 1.4 to 1.6 log CFU/leaf, but the treatments did not completely inactivate the pathogen in the wash solution. Increasing the washing time to 30 s increased the reductions to 1.7 to 2.3 log CFU/leaf. Sequential washing in SAEO water for 15 s and then chilling in SAEO water for 15 min also increased the reductions to 2.0 to 2.4 log CFU/leaf, and no cell survived in chilling solution after treatment. Washing tomatoes with SAEO water for 8 s reduced E. coli O157:H7 by 5.4 to 6.3 log CFU/tomato. The reductions were increased to 6.6 to 7.6 log CFU/tomato by increasing the washing time to 15 s. Results suggested that application of SAEO water to wash and chill lettuce and tomatoes in food service kitchens could minimize cross-contamination and reduce the risk of E. coli O157:H7 present on the produce.

Microbe(s): Escherichia coli O157:H7

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Treatment of fresh fruits and vegetables with electrolyzed water (EW) has been shown to kill or reduce foodborne pathogens. We evaluated the efficacy of EW in killing Escherichia coli O157:H7 on iceberg lettuce, cabbage, lemons, and tomatoes by using washing and/or chilling treatments simulating those followed in some food service kitchens. Greatest reduction levels on lettuce were achieved by sequentially washing with 14-A (amperage) acidic EW (AcEW) for 15 or 30 s followed by chilling in 16-A AcEW for 15 min. This procedure reduced the pathogen by 2.8 and 3.0 log CFU per leaf, respectively, whereas washing and chilling with tap water reduced the pathogen by 1.9 and 2.4 log CFU per leaf. Washing cabbage leaves for 15 or 30 s with tap water or 14-A AcEW reduced the pathogen by 2.0 and 3.0 log CFU per leaf and 2.5 to 3.0 log CFU per leaf, respectively. The pathogen was reduced by 4.7 log CFU per lemon by washing with 14-A AcEW and 4.1 and 4.5 log CFU per lemon by washing with tap water for 15 or 30 s. A reduction of 5.3 log CFU per lemon was achieved by washing with 14-A alkaline EW for 15 s prior to washing with 14-A AcEW for 15 s. Washing tomatoes with tap water or 14-A AcEW for 15 s reduced the pathogen by 6.4 and 7.9 log CFU per tomato, respectively. Application of AcEW using procedures mimicking food service operations should help minimize cross-contamination and reduce the risk of E. coli O157:H7 being present on produce at the time of consumption.

Microbe(s): Escherichia coli O157:H7

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The Nernst equations between the oxidation reduction potential (ORP), the concentration of hypochlorous acid and chlorine and the value of pH in electrolyzed oxidizing water (EOW) were developed in three parts, which were in agreement in the measured values. The role of ORP in EOW for killing Escherichia coli O157:H7 was studied. The inactivation effect of EOW on E. coli O157:H7 was also studied by spectroscopy measurements, and the inactivation mechanism was proposed.

Microbe(s): Escherichia coli O157:H7

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Inoculated strawberries were treated with deionized water (control), electrolyzed oxidizing (EO) water (23 and 55 mg/L of residual chlorine), and chlorinated water (55 mg/L of residual chlorine), either with or without ultrasonication. Inoculated broccoli was treated with EO water containing 55 and 100 mg/L of residual chlorine and chlorinated water with 100 mg/L of residual chlorine. Treatments were conducted for 1 and 5 min at temperatures of 4 and 24C, respectively. Dipping strawberries and broccoli into EO water or chlorinated water significantly (P < 0.05) reduced the Escherichia coli O157:H7 counts compared with inoculated controls. Dipping inoculated strawberries with chlorinated water or EO water with ultrasonication reduced E. coli O157:H7 cells by 0.7 to 1.9 log cfu/g depending on the treatment time and treatment solution temperature. Dipping inoculated broccoli into chlorinated water or EO water with ultrasonication for 1 or 5 min reduced the bacterial population by 1.2 to 2.2 log cfu/g. Significant (P < 0.05) reductions in pathogen populations were observed when produce was treated with EO water in conjunction with ultrasonication. Results revealed that EO water was either more than or as effective as chlorinated water in killing E. coli O157:H7 cells on strawberries and broccoli.

Microbe(s): Escherichia coli O157:H7

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This study compared the efficacy of chlorine (20 200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20 200 ppm chlorite ion concentration, Sanova ), and aqueous chlorine dioxide (20 200 ppm chlorite ion concentration, TriNova ) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova , Sanova , and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of ~ 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The efficacy of newly developed low concentration electrolyzed water (LcEW) was investigated to inactivate the pathogens on spinach leaves as a convenient and safe alternative sanitizer and it was compared to other sanitizers. Spinach leaves were inoculated with Escherichia coli O157:H7 and Listeria monocytogenes and dip treated with deionized water (DIW), LcEW, strong acid electrolyzed water (SAEW), aqueous ozone (AO), 1% citric acid (CA) and sodium hypochlorite solution (NaOCl) for 3 min at room temperature (23 +/- 2 C). For all pathogens, the similar pattern of microbial reduction on spinach was apparent with LcEW and SAEW washing. In the present study, it was found that LcEW inactivated, at maximum, 1.64-2.80 log cfu/g and DIW resulted in lowest reduction, 0.31-0.95 log cfu/g of background or pathogenic microflora present on spinach leaves compared to the unwashed control. The findings of this study indicate that LcEW and SAEW did not differ significantly (P > 0.05) in reducing background or pathogenic microflora on spinach and LcEW may be a promising sanitizer for washing vegetables without environmental pollution instead of using electrolyzed oxidizing (EO) water or SAEW.

Microbe(s): Escherichia coli, Staphylococcus aureus, Salmonella spp.

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In the current study, the effectiveness of slightly acidic electrolyzed water (SAEW) on an in vitro inactivation of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella spp. was evaluated and compared with other sanitizers. SAEW (pH 5.6, 23 mg/l available chlorine concentration; ACC; and 940 mV oxidation reduction potential; ORP) was generated by electrolysis of dilute solution of HCl (2%) in a chamber of a non-membrane electrolytic cell. One milliliter of bacteria suspension (ca. 10-11 log10CFU/ml) was mixed with 9 ml of SAEW, strong acidic electrolyzed water (StAEW; ca. 50 mg/l ACC), sodium hypochlorite solution (NaOCl; ca.120 mg/l ACC) and distilled water (DW) as control and treated for 60 s. SAEW effectively reduced the population of E. coli, S. aureus and Salmonella spp. by 5.1, 4.8, and 5.2 log10CFU/ml. Although, ACC of SAEW was more than 5 times lower than that of NaOCl solution, they showed no significant bactericidal difference (p > 0.05). However, the bactericidal effect of StAEW was significantly higher (p < 0.05) than SAEW and NaOCl solution in all cases. When tested with each individual test solution, E. coli, S. aureus and Salmonella spp. reductions were not significantly different (p > 0.05). These findings indicate that SAEW with low available chlorine concentration can equally inactivate E. coli, S. aureus and Salmonella spp. as NaOCl solution and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.

Microbe(s):  Listeria monocytogenes, Morganella morganii

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Listeria monocytogenes and Morganella morganii have been implicated in listeriosis outbreaks and histamine fish poisoning, respectively. Possible sources of contamination of food products include processing equipment, food handlers, and fish smokehouses. Treatment of food preparation surfaces and of whole fish during handling with agents such as, electrolyzed oxidizing (EO) water, could reduce biofilm formation on seafood products and in seafood processing plants. We examined the efficacy of EO water against L. monocytogenes and M. morganii biofilms using the MBEC Assay System (Innovotech Inc.), conveyor belt coupons, and raw fish surfaces. The MBEC Assay System was used to assess the activity of EO water against 24-h biofilms of 90 L. monocytogenes strains and five M. morganii strains. Biofilms were exposed to PBS or EO water for 0 (control), 5, 15, and 30 min. All bacterial isolates were susceptible (reduction of 7 log10CFU) to treatment with EO water for 5 min based on results obtained using this assay system. EO water was used to treat four L. monocytogenes strains and one M. morganii strain attached to conveyor belt coupons and fish surfaces. Three L. monocytogenes strains and one M. morganii strain on belt coupons were reduced by 12.5 log10CFU/cm2 by exposure (5 min) to EO water compared to exposure to sterile distilled water. Strain to strain variability in susceptibility to EO water was evidenced by the fact that numbers of one L. monocytogenes strain were not reduced by EO water treatment of belt surfaces. EO water was not effective against L. monocytogenes and M. morganii on fish surfaces as growth occurred during cold storage. These results suggest that exposure of conveyor belts to EO water for a minimum of 5 min could assist in the removal of some biofilms. Removal of food residue with continuous or intermittent spraying of food processing equipment (e.g., conveyor belts, slicers) could reduce or prevent further biofilm formation. Additional sanitizers must be investigated for activity against bacteria associated with raw fish.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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Low concentration electrolyzed water (LcEW) has been proved to be an effective sanitizer against pathogens in cell suspensions as well as pathogens and spoilage organisms attached to vegetables, poultry and meat. In this study, effect of current, electrolysis time and salt concentration on physical properties (pH, ORP and ACC) and inactivation efficacy of LcEW was monitored. Pure cultures of Escherichia coli O157:H7 and Listeria monocytogenes were prepared and exposure treatment was performed for bacteria inactivation study in cell suspensions at room temperature (23 2 C). Our results showed increased reduction of both pathogens with the increase in current. Changes of current also affected the ACC, pH and ORP values of the tested solution. Values of ACC, pH and ORP were increased with the increase in current. Log reduction of 4.9 5.6 log CFU/mL for both pathogens was achieved when the current was increased from 1.15 to 1.45 A. Electrolysis time and percent of salt concentration also influenced the physical properties of LcEW. Stability of LcEW was also investigated under different conditions and it was observed that LcEW produced with increased electrical current was more stable during storage. Therefore, current might influence the properties and sanitizing effect of LcEW.

Microbe(s): Escherichia coli, Listeria innocua

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The effectiveness of neutral electrolyzed water (NEW) to sanitize cutting boards used for food preparation was investigated. Cutting boards made of hardwood and bamboo were inoculated with Escherichia coli K12 and Listeria innocua, dried for 1 h, washed, rinsed and sanitized with NEW, sodium hypochlorite (NaClO) solution, or tap water (control). After each washing protocol, surviving bacterial populations were determined. Results showed that both NEW and NaClO sanitizing solutions produced similar levels of bacterial reductions. In manual washing, the population reductions by NEW and NaClO were 3.4 and 3.6 log10 CFU/100 cm2 for E. coli, and 4.1 and 3.9 log10 CFU/100 cm2 for L. innocua, respectively. In the automatic washing, the reductions by NEW and NaClO were 4.0 and 4.0 log10 CFU/100 cm2 for E. coli, and 4.2 and 3.6 log10 CFU/100 cm2 for L. innocua, respectively. No significant differences (P > 0.05) were observed in surviving bacteria counts when comparing board material types.

Microbe(s): Listeria monocytogenes

ABSTRACT – Full Text PDF

The objective of this study was to develop a model of the growth of Listeria monocytogenes in pork untreated or treated with low concentration electrolyzed water (LcEW) and strong acid electrolyzed water (SAEW), as a function of temperature. The experimental data obtained under different temperatures (4, 10, 15, 20, 25, and 30 C) were fitted into the modified Gompertz model to generate the growth parameters including specific growth rate (SGR) and lag time (LT) with high coefficients of determination (R2 >0.97). The obtained SGR and LT were employed to develop square root models to evaluate the effects of storage temperature on the growth kinetics of L. monocytogenes in pork. The values of bias factor (0.924-1.009) and accuracy factor (1.105-1.186), which were regarded as acceptable, demonstrated that the obtained models could provide good and reliable predictions and be suitable for the purpose of microbiological risk assessment of L. monocytogenes in pork.

Microbe(s): Escherichia coli

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Electrolyzed – oxidizing (EO) water is a relatively new method that has been utilized for killing pathogens in agriculture, medical sterilization and food sanitation. This water is generated by passing sodium chloride solution through EO water generator. In this study, the EO water was used to treat holy basil inoculated with Escherichia coli. The initial pH and oxidation – reduction potential (ORP) of EO water were 2.09 and 1200 mV, respectively. The treatments changed ORP to 800,950 and 1100 mV. The contact times were 10,30 and 60 min. In pure culture, E. coli viable counts in the sample treated with EO water were reduced to undetectable levels at all ORP and times. However no reduction in E. coli counts was achieved in the control sample (treated with deionized water). The initial population of E. coli was about 8.5 log10 CFU / ml which was inoculated on 5 g of holy basil. Results showed that the treatment treated with EO water was reduced about 2 log10 CFU / ml in ORP 800 and 950 mV, 4 log10 CFU / ml in ORP 1100 mV for 10 min. When the contact time increased to 30 min, the reduction of E. coli count was about 3 log 10 CFU / ml in ORP 950 mV and 5 log10 CFU / ml in ORP 1100 mV. But the reduction was not different from 10 min when treated with ORP 800 mV. When the contact time increased to 60 min, the reduction of E. coli count was about 3 log10 CFU / ml in ORP 800 mV, 4 log10 CFU / ml in ORP 950 mV. and 6 log10 CFU / ml in ORP 1100 mV. These results could be concluded that the ORP of EO water and contact time significantly inactivated E. coli.

Microbe(s): Escherichia coli O157:H7, Salmonella

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Cut lettuce dip-inoculated with Escherichia coli O157:H7 and Salmonella was treated with alkaline electrolyzed water (AlEW) at 20 C for 5 min, and subsequently washed with acidic electrolyzed water (AcEW) at 20 C for 5 min. Pre-treatment with AlEW resulted in an approximate 1.8 log10 cfu/g reduction of microbial populations, which was significantly (p 0.05) greater than microbial reductions resulting from other pre-treatment solutions, including distilled water and AcEW. Repeated AcEW treatment did not show a significant bacterial reduction. Mildly heated (50 C) sanitizers were compared with normal (20 C) or chilled (4 C) sanitizers for their bactericidal effect. Mildly heated AcEW and chlorinated water (200 ppm free available chlorine) with a treatment period of 1 or 5 min produced equal reductions of pathogenic bacteria of 3 log10 and 4 log10 cfu/g, respectively. The procedure of treating with mildly heated AlEW for 5 min, and subsequent washing with chilled (4 C) AcEW for period of 1 or 5 min resulted in 3 4 log10 cfu/g reductions of both the pathogenic bacterial counts on lettuce. Extending the mild heat pre-treatment time increased the bactericidal effect more than that observed from the subsequent washing time with chilled AcEW. The appearance of the mildly heated lettuce was not deteriorated after the treatment. In this study, we have illustrated the efficacious application of AlEW as a pre-wash agent, and the effective combined use of AlEW and AcEW.

Microbe(s): Listeria monocytogenes, Escherichia coli O157:H7

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Acidic electrolyzed water (AcEW) was used as frozen AcEW (AcEW-ice) for inactivation of Listeria monocytogenes and Escherichia coli O157:H7 on lettuce. AcEW-ice was prepared from AcEW with 20, 50, 100, and 200 ppm of available chlorine by freezing at 40 C and generated 30, 70, 150, and 240 ppm of chlorine gas (Cl2), respectively. The AcEW-ice was placed into styrene-foam containers with lettuce samples at 20 C for 24 h. Although AcEW-ice generating 30 ppm Cl2 had no effect on L. monocytogenes cell counts, AcEW-ice generating 70 to 240 ppm of Cl2 significantly (P < 0.05) reduced L. monocytogenes by ca. 1.5 log CFU/g. E. coli O157:H7 cell counts were reduced by 1.0 log CFU/g with AcEW-ice generating 30 ppm of Cl2. AcEW-ice generating 70 and 150 ppm of Cl2 reduced E. coli O157:H7 by 2.0 log CFU/g. Further significant reduction of E. coli O157:H7 (2.5 log CFU/g) was demonstrated by treatment with AcEW-ice generating 240 ppm of Cl2. However, treatment with AcEW-ice generating 240 ppm of Cl2 resulted in a physiological disorder resembling leaf burn. AcEW-ice that generated less than 150 ppm of Cl2 had no effect on the surface color of the lettuce. AcEW-ice, regardless of the concentration of the emission of Cl2, had no effect on the ascorbic acid content in the lettuce. The weight ratio of lettuce to AcEW-ice required was determined to be over 1:10. The bactericidal effect of AcEW-ice appeared within the first 2 h. The use of AcEW-ice provides simultaneously for low temperature storage and inactivation of bacteria.

Microbe(s): Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes

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Fresh-cut lettuce samples inoculated with S. Typhimurium, E. coli O157:H7 or L. monocytogenes were dipped into 300 ppm electrolyzed water (EW) at pH 4 to 9 and 30 C for 5 min. The effects of treatment pH on bacterial reduction and visual quality of the lettuce were determined. The treatments at pH 4 and 8 resulted in the most effective inactivation of E. coli O157:H7, but the effect of pH was not significant (P > 0.05) for S. Typhimurium and L. monocytogenes. The treatment at pH 7 retained the best visual quality of lettuce, and achieved a reduction of approximately 2 log CFU/g for above 3 bacteria.

Microbe(s): Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes, Escherichia coli

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Research was conducted to compare the effectiveness of electrolyzed oxidative (EO) water applied using an electrostatic spraying system (ESS) for killing populations of bacteria that are of concern to the poultry industry. Populations of pathogenic bacteria (Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes), and the indicator bacterium Escherichia coli were applied to eggs and allowed to attach for 1 h. EO water completely eliminated all Salmonella typhimurium on 3, 7, 1, and 8 out of 15 eggs in Repetitions (Rep) 1, 2, 3, and 4, respectively, even when very high inoculations were used. EO water completely eliminated all Staphylococcus aureus on 12, 11, 12, and 11 out of 15 eggs in Rep 1, 2, 3, and 4, respectively. EO water completely eliminated all Listeria monocytogenes on 8, 13, 12, and 14 out of 15 eggs in Reps 1, 2, 3, and 4, respectively. EO water completely eliminated all Escherichia coli on 9, 11, 15, and 11 out of 15 eggs in Reps 1, 2, 3, and 4, respectively. Even when very high concentrations of bacteria were inoculated onto eggs (many times higher than would be encountered in industrial situations), EO water was found to be effective when used in conjunction with electrostatic spraying for eliminating pathogenic and indicator populations of bacteria from hatching eggs.

Microbe(s): Salmonella enteritidis, Escherichia coli

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During commercial processing, eggs are washed in an alkaline detergent and then rinsed with chlorine to reduce dirt, debris, and microorganism levels. The alkaline and acidic fractions of electrolyzed oxidizing (EO) water have the ability to fit into the 2-step commercial egg washing process easily if proven to be effective. Therefore, the efficacy of EO water to decontaminate Salmonella Enteritidis and Escherichia coli K12 on artificially inoculated shell eggs was investigated. For the in vitro study, eggs were soaked in alkaline EO water followed by soaking in acidic EO water at various temperatures and times. Treated eggs showed a reduction in population between > or = 0.6 to > or =2.6 log10 cfu/g of shell for S. Enteritidis and > or =0.9 and > or =2.6 log10 for E. coli K12. Log10 reductions of 1.7 and 2.0 for S. Enteritidis and E. coli K12, respectively, were observed for typical commercial detergent-sanitizer treatments, whereas log10 reductions of > or =2.1 and > or =2.3 for S. Enteritidis and E. coli K12, respectively, were achieved using the EO water treatment. For the pilot-scale study, both fractions of EO water were compared with the detergent-sanitizer treatment using E. coli K12. Log10 reductions of > or = 2.98 and > or = 2.91 were found using the EO water treatment and the detergent-sanitizer treatment, respectively. The effects of 2 treatments on egg quality were investigated. EO water and the detergent-sanitizer treatments did not significantly affect albumen height or eggshell strength however, there were significant affects on cuticle presence. These results indicate that EO water has the potential to be used as a sanitizing agent for the egg washing process.

Microbe(s): Escherichia coli O157: H7

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To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to <700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24 C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to 848 mV. When stored in the dark, the diluted EO waters retained an ORP of >848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4 C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

Microbe(s): Escherichia coli O157: H7, Listeria monocytogenes

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Raw fish is prone to risk of microbial outbreaks due to contamination of pathogenic microorganisms. Escherichia coli O157:H7 and Listeria monocytogenes are among the pathogens associated with raw fish. Therefore, it is important to treat raw fish to inactivate pathogenic microorganisms. Electrolyzed oxidizing water is novel antimicrobial agent containing acidic solution with a pH of 2.6- 2.9, ORP of 1120 1180 mV, and 76-90 ppm free chlorine, and alkaline solution with a pH of 11.5 and ORP of 795 mV. This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) water for inactivation of E. coli O157:H7 and L. monocytogenes Scott A on the surfaces (muscle and skin surfaces) of inoculated salmon fillets. Inoculated salmon fillets were treated only with acidic EO water at 22C and 35C and sodium hypochlorite solution (90 ppm free chlorine) as control at 22C for 2, 4, 8, 16, 32, and 64 min, respectively. For the treatment with alkaline EO water followed by acidic EO water, a response surface model was developed to predict effective times in the range of 5-30 min and temperatures in the range of 22-35C for both alkaline and acidic water treatments. The acidic EO water treatments resulted in reductions of population of L. monocytogenes Scott A ranging from 0.40 log10 CFU/g (60 %) at 22oC to 1.12 log10 CFU/g (92.3 %) at 35oC. Treatment of inoculated salmon fillets in acidic EO water reduced E. coli O157:H7 populations by 0.49 log10 CFU/g (67 %) 22C and 1.07 log10 CFU/g (91.1 %) at 35C, respectively. Response surface analysis for alkaline EO water treatment followed by acidic treatment demonstrated that, maximum log reduction of 1.33 log10 CFU/g (95.3 %) for E. coli O157:H7 and 1.09 log10 CFU/g (91.9 %) for L. monocytogenes Scott A.

Microbe(s): Escherichia coli

ABSTRACT – Full Text PDF

Recently, several reports about sterilization effect of electrolyzed water have been published. The electrolyzed water is expected as one of attractive application for sanitation of fresh food, however, to install this electrolyzed water, we have to clear the potential of the microorganism control for real food. In this paper, we try to reveal the mechanism of the microorganism control, and also try to check the food quality change during the treatment. Therefore, to evaluate the effect of the electrolyzed water, we examined the several test for making sterilization mechanism clear and observed microorganism behavior on food surface. At first, for the purpose of making sterilization effects clear in vitro condition, we did microorganism test with several injection ratio and number. Then, we studied the effects of catalase on the enumeration of stressed Escherichia coli cells after acidic electrolyzed water treatment. Moreover, we studied sterilization effect of acidic electrolyzed water for E. coli on an agar block on the assumption as one of food model. In addition, we studied sterilization effects for sliced raw tuna as one sample of food surface treatment. The change in the quality of food surface was observed by scanning electron microscope, color meter and so on. Steriliaation effects are dependent the condition of injection ratio and mixing numbers. These results suggest that it is important to keep available chlorine concentration for keeping the potential to the microorganisms control. The increasing of E. coli number with the addition of catalase was suggested that the weak concentration of electrolyzed water gave the injured microbes. The Observation of cultivated E. coli behavior on agar block showed the microorganism behavior. Acidic electrolyzed water sterilizes microorganisms on sliced raw tuna, however, after treatment, the color change of surface of tuna and the protein denaturation were observed. These results suggest that when the electrolyzed water treatment is applied to control the microorganism on surface, the effect against food surface must be considered.

Microbe(s): Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes

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Acidic electrolyzed water (AC-EW) has strong bactericidal activity against foodborne pathogens on fresh vegetables. However, the efficacy of AC-EW is influenced by soil or other organic materials present. This study examined the bactericidal activity of AC-EW in the presence of organic matter, in the form of bovine serum against foodborne pathogens on the surfaces of green onions and tomatoes. Green onions and tomatoes were inoculated with a culture cocktail of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes. Treatment of these organisms with AC-EW containing bovine serum concentrations of 5, 10, 15, and 20 ml/l was performed for 15 s, 30 s, 1 min, 3 min and 5 min. The total residual chlorine concentrations of AC-EW decreased proportional to the addition of serum. The bactericidal activity of AC-EW also decreased with increasing bovine serum concentration, whereas unamended AC-EW treatment reduced levels of cells to below the detection limit (0.7 logCFU/g) within 3 min.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

ABSTRACT – Full Text PDF

One milliliter of culture containing a five-strain mixture of Escherichia coli O157:H7 (1010 CFU) was inoculated on a 100-cm2 area marked on unscarred cutting boards. Following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 C or 35 C for 10 or 20 min; 45 C for 5 or 10 min; or 55 C for 5 min. After each temperature-time combination, the surviving population of the pathogen on cutting boards and in soaking water was determined. Soaking of inoculated cutting boards in electrolyzed oxidizing water reduced E. coli O157:H7 populations by 5.0 log CFU/100 cm2 on cutting boards. However, immersion of cutting boards in deionized water decreased the pathogen count only by 1.0 to 1.5 log CFU/100 cm2. Treatment of cutting boards inoculated with Listeria monocytogenes in electrolyzed oxidizing water at selected temperature-time combinations (23 C for 20 min, 35 C for 10 min, and 45 C for 10 min) substantially reduced the populations of L. monocytogenes in comparison to the counts recovered from the boards immersed in deionized water. E. coli O157:H7 and L. monocytogenes were not detected in electrolyzed oxidizing water after soaking treatment, whereas the pathogens survived in the deionized water used for soaking the cutting boards. This study revealed that immersion of kitchen cutting boards in electrolyzed oxidizing water could be used as an effective method for inactivating foodborne pathogens on smooth, plastic cutting boards.

Microbe(s): Listeria monocytogenes, Escherichia coli O157 : H7

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Effects of alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaClO), deionized water (DIW), 1% citric acid (CA) alone, and combinations of AlEW with 1% CA (AlEW + CA), in reducing the populations of spoilage bacteria and foodborne pathogens on cabbage were investigated at various dipping times (3, 5, and 10 min) with different dipping temperatures (1, 20, 40, and 50 C). Inhibitory effect of the selected optimal treatment against Listeria monocytogenes and Escherichia coli O157 : H7 on cabbage were also evaluated. Compared to the untreated control, AlEW treatment most effectively reduced the numbers of total bacteria, yeast, and mold, followed by AcEW and 100-ppm NaClO treatments. All treatments dip washed for 5 min significantly reduced the numbers of total bacteria, yeast, and mold on cabbage. With increasing dipping temperature from 1 to 50 C, the reductions of total bacteria, yeast, and mold were significantly increased from 0.19 to 1.12 log CFU/g in the DIW wash treatment (P < 0.05). Combined 1% CA with AlEW treatment at 50 C showed the reduction of around 3.98 and 3.45 log CFU/g on the total count, and yeast and mold, effective reduction of L. monocytogenes (3.99 log CFU/g), and E. coli O157 : H7 (4.19 log CFU/g) on cabbage. The results suggest that combining AlEW with CA could be a possible method to control foodborne pathogens and spoilage bacteria effectively on produce.

Microbe(s): Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis

ABSTRACT – Full Text PDF

Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution (1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl2, HOCl/ClO-). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900 mV. The biocidal activity of near-neutral EO water was evaluated at 25 C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120 ppm total residual chlorine (TRC) and 10 min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7 log10 CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310 ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10 min) treatment of spinach at 100 and 120 ppm TRC resulted in a 4.0-5.0 log10 CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10 min) of lettuce at 100 and 120 ppm TRC reduced bacterial counts of E. coli by 0.24-0.25 log10 CFU/mL and reduced all other organisms by 2.43-3.81 log10 CFU/mL.

Microbe(s): Escherichia coli K12, Listeria innocua, Pseudomonas putida

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This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PROSAN (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PROSAN and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of < 1 log CFU was obtained for the fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly (P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for crosscontamination.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium

ABSTRACT – Full Text PDF

Strong acid electrolyzed water (SAEW) has a very limited application due to its low pH value (< 2.7) and corrosive characteristics. Thus, we developed new low concentration electrolyzed water (LcEW). The efficacy of LcEW under various treatment conditions for the inactivation of different foodborne pathogens in pure culture was evaluated and compared with SAEW. The efficiency of LcEW and SAEW for the inactivation of predominant foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium) with different dipping times (1, 3, 5, 7 and 10 min), pH values (2.5, 4.0, 5.0, 6.0 and 9.0) and temperatures (4, 15, 23, 35 and 50 C) were determined. Reductions of bacterial populations of 1.7 to 6.6 log10 CFU/mL in various treated conditions in cell suspensions were observed after treatment with LcEW and SAEW, compared to the untreated control. Dip washing (1 min at 35 C) of lettuce leaves in both electrolyzed water resulted in 2.5 to 4.0 log10 CFU/g compared to the unwashed control. Strong inactivation effects were observed in LcEW, and no significant difference (p > 0.05) was observed between LcEW and SAEW. The effective form of chlorine compounds in LcEW was almost exclusively hypochlorous acid (HOCl), which has strong antimicrobial activity and leaves no residuals due to the low concentration of residual chlorine. Thus, LcEW could be widely applied as a new sanitizer in the food industry.

Microbe(s): Escherichia coli O157:H7

ABSTRACT – Full Text PDF

This study investigates the properties of electrolyzed oxidizing (EO) water for the inactivation of pathogen and to evaluate the chemically modified solutions possessing properties similar to EO water in killing Escherichia coli O157:H7. A five-strain cocktail (1010 CFU/ml) of E. coli O157:H7 was subjected to deionized water (control), EO water with 10 mg/liter residual chlorine (J.A.W-EO water), EO water with 56 mg/liter residual chlorine (ROX-EO water), and chemically modified solutions. Inactivation (8.88 log10 CFU/ml reduction) of E. coli O157:H7 occurred within 30 s after application of EO water and chemically modified solutions containing chlorine and 1% bromine. Iron was added to EO or chemically modified solutions to reduce oxidation reduction potential (ORP) readings and neutralizing buffer was added to neutralize chlorine. J.A.W-EO water with 100 mg/liter iron, acetic acid solution, and chemically modified solutions containing neutralizing buffer or 100 mg/liter iron were ineffective in reducing the bacteria population. ROX-EO water with 100 mg/liter iron was the only solution still effective in inactivation of E. coli O157:H7 and having high ORP readings regardless of residual chlorine. These results suggest that it is possible to simulate EO water by chemically modifying deionized water and ORP of the solution may be the primary factor affecting microbial inactivation.

Microbe(s): Escherichia coli

ABSTRACT – Full Text PDF

Hypochlorous acid (HOCl) is probably the most widely used disinfectant worldwide and has an important role in inflammatory reaction and in human resistance to infection. However, the nature and mechanisms of its bactericidal activity are still poorly understood. Bacteria challenged aerobically with HOCl concentrations ranging from 9.5 to 76 M exhibit higher ability to form colonies anaerobically than aerobically. Conversely, aerobic plating greatly increased lethality after an anaerobic HOCl challenge, although anaerobic survival did not depend on whether HOCl exposure was aerobic or anaerobic. Even a short transient exposure to air after anaerobic HOCl challenge reduced anaerobic survival, indicative of immediate deleterious effects of oxygen. Exposure to HOCl can cause lethal DNA damage as judged by the fact that recA sensitivity to HOCl was oxygen dependent. Antioxidant defenses such as reduced glutathione and glucose-6-phosphate dehydrogenase were depleted or inactivated at 10 M HOCl, while other activities, such as superoxide dismutase, dropped only above 57 M HOCl. Cumulative deficiencies in superoxide dismutase and glucose-6-phosphate dehydrogenase rendered strains hypersensitive to HOCl. This indicates that part of HOCl toxicity on Escherichia coli is mediated by reactive oxygen species during recovery.

Microbe(s): Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes

ABSTRACT – Full Text PDF

The ability of electrolyzed water (EW) to inactivate foodborne pathogens on the surfaces of lettuce and spinach was investigated. Lettuce and spinach leaves were inoculated with a cocktail of 3 strains each of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated with acidic electrolyzed water (AC-EW), alkaline electrolyzed water (AK-EW), alkaline electrolyzed water followed by acidic electrolyzed water (sequential treatment, AK-EW + AC-EW), deionized water followed by acidic electrolyzed water (sequential treatment, DW + AC-EW), and deionized water (control, DW) for 15, 30 s, and 1, 3, and 5 min at room temperature (22 2 C). For all 3 pathogens, the same pattern of microbial reduction on lettuce and spinach were apparent. The relative efficacy of reduction was AC-EW > DW + AC-EW = AK-EW + AC-EW > AK-EW > control. After a 3-min treatment of AC-EW, the 3 tested pathogens were reduced below the detection limit (0.7 log). DW + AC-EW and AK-EW + AC-EW produced the same levels of reduction after 5 min when compared to the control. AK-EW did not reduce levels of pathogens even after a 5-min treatment on lettuce and spinach. Results suggest that AC-EW treatment was able to significantly reduce populations of the 3 tested pathogens from the surfaces of lettuce and spinach with increasing time of exposure.

Microbe(s): Escherichia coli O157: H7

ABSTRACT – Full Text PDF

Survival of Escherichia coli O157:H7 was studied on strawberry, a fruit that is not usually washed during production, harvest, or postharvest handling. Two strains of the bacteria were tested separately on the fruit surface or injected into the fruit. Both strains of E. coli O157:H7 survived externally and internally at 23 C for 24 h and at 10, 5, and 20 C for 3 days. The largest reduction in bacterial population occurred at 20 C and on the fruit surface during refrigeration. In all experiments, the bacteria inside the fruit either survived as well as or better than bacteria on the surface, and ATCC 43895 frequently exhibited greater survival than did ATCC 35150. Two strains of E. coli also survived at 23 C on the surface and particularly inside strawberry fruit. Chemical agents in aqueous solution comprising NaOCl (100 and 200 ppm), Tween 80 (100 and 200 ppm), acetic acid (2 and 5%), Na3PO4 (2 and 5%), and H2O2 (1 and 3%) were studied for their effects on reduction of surface-inoculated (108 CFU/ml) E. coli O157:H7 populations on strawberry fruit. Dipping the inoculated fruit in water alone reduced the pathogen population about 0.8 log unit. None of the compounds with the exception of H2O2 exhibited more than a 2-log CFU/g reduction of the bacteria on the fruit surface. Three percent H2O2, the most effective chemical treatment, reduced the bacterial population on strawberries by about 2.2 log CFU/g.

Microbe(s): Escherichia coli O157:H7, Salmonella enteritidis, Listeria monocytogenes

ABSTRACT – Full Text PDF

The efficacy of electrolyzed oxidizing water for inactivating. Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes was evaluated. A five-strain mixture of E. coli O157:H7,S. enteritidis, or L. monocytogenes of approximately 108 CFU/ml was inoculated in 9 ml of electrolyzed oxidizing water (treatment) or 9 ml of sterile, deionized water (control) and incubated at 4 or 23 C for 0, 5, 10, and 15 min; at 35 C for 0, 2, 4, and 6 min; or at 45 C for 0, 1, 3, and 5 min. The surviving population of each pathogen at each sampling time was determined on tryptic soy agar. At 4 or 23 C, an exposure time of 5 min reduced the populations of all three pathogens in the treatment samples by approximately 7 log CFU/ml, with complete inactivation by 10 min of exposure. A reduction of 7 log CFU/ml in the levels of the three pathogens occurred in the treatment samples incubated for 1 min at 45 C or for 2 min at 35 C. The bacterial counts of all three pathogens in control samples remained the same throughout the incubation at all four temperatures. Results indicate that electrolyzed oxidizing water may be a useful disinfectant, but appropriate applications need to be validated.

Microbe(s): Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes

ABSTRACT – Full Text PDF

Recent foodborne outbreaks implicating spinach and lettuce have increased consumer concerns regarding the safety of fresh produce. While the most common commercial antimicrobial intervention for fresh produce is wash water containing 50 to 200 ppm chlorine, this study compares the effectiveness of acidified sodium chlorite, chlorine, and acidic electrolyzed water for inactivating Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated onto leafy greens. Fresh mixed greens were left uninoculated or inoculated with approximately 6 log CFU/g of E. coli O157:H7, Salmonella, and L. monocytogenes and treated by immersion for 60 or 90 s in different wash solutions (1:150, wt/vol), including 50 ppm of chlorine solution acidified to pH 6.5, acidic electrolyzed water (pH 2.1 0.2, oxygen reduction potential of 1,100 mV, 30 to 35 ppm of free chlorine), and acidified sodium chlorite (1,200 ppm, pH 2.5). Samples were neutralized and homogenized. Bacterial survival was determined by standard spread plating on selective media. Each test case (organism treatment time) was replicated twice with five samples per replicate. There was no difference (P 0.05) in the time of immersion on the antimicrobial effectiveness of the treatments. Furthermore, there was no difference (P 0.05) in survival of the three organisms regardless of treatment or time. Acidified sodium chlorite, resulted in reductions in populations of 3 to 3.8 log CFU/g and was more effective than chlorinated water (2.1 to 2.8 log CFU/g reduction). These results provide the produce industry with important information to assist in selection of effective antimicrobial strategies.

Microbe(s): Listeria monocytogenes

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An electrochemical treatment system consisting of a pulsed electrical power supply and an electrical treatment chamber was designed and evaluated for inactivation Listeria monocytogenes in recirculated brine for chilling processed bacons. The brine was tested under different currents and temperatures. An average D-value of 1.61 min in the storage tank could be achieved at 7 mA/cm3 current with the fresh brine (t = 0 h). For the spent brine (t = 20 h), the D-value was 2.5 min in the treatment chamber at 35 mA/cm3. The average D-values in the treatment chamber were approximately 2.5 min at all three temperatures (4, 0, -8 8C) at 35 mA/cm3.

Microbe(s): Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus

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This study evaluated the efficacy of neutral electrolyzed water (NEW; 64.1 mg/liter of active chlorine) to reduce populations of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes on plastic and wooden kitchen cutting boards. Its effectiveness was compared with that of a sodium hypochlorite solution (NaClO; 62.3 mg/liter of active chlorine). Inoculated portions of cutting boards were rinsed in either NEW or NaClO solutions, or deionized water (control). Plastic boards were rinsed for 1 min and wooden boards for 1 and 5 min. After each treatment, the surviving population of each strain was determined on the surface and in the soaking water. No significant difference (P 0.05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO). However, a significant difference (P 0.05) was revealed between surface materials after 1 min of washing. Whereas in plastic boards the initial bacterial populations were reduced by 5 log CFU/50 cm2, in wooden cutting boards they underwent a reduction of <3 log CFU/50 cm2. A 5-min exposure time yielded reductions of about 4 log CFU/50 cm2. The surviving populations of all bacteria in NEW and NaClO washing solutions were <1 log CFU/ml after soaking both surfaces. This study revealed that NEW treatment is an effective method for reducing microbial contamination on plastic and wooden cutting boards. NEW efficacy was comparable to that of NaClO, with the advantage of having a larger storage time.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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Antibacterial activity of electrolyzed oxidizing (EO) water prepared from 0.05% or 0.10% (w/v) sodium chloride (NaCl) solutions against indigenous bacteria associated with fresh strawberries (Fragaria ananassa) was evaluated. The efficacy of EO water and sodium hypochlorite (NaOCl) solution in eliminating and controlling the growth of Listeria monocytogenes and Escherichia coli O157:H7 inoculated onto strawberries stored at 4 +/- 1 C up to 15 d was investigated at exposure time of 1, 5, or 10 min. Posttreatment neutralization of fruit surfaces was also determined. More than 2 log10 CFU/g reductions of aerobic mesophiles were obtained in fruits washed for 10 or 15 min in EO water prepared from 0.10% (w/v) NaCl solution. Bactericidal activity of the disinfectants against L. monocytogenes and E. coli O157:H7 was not affected by posttreatment neutralization, and increasing exposure time did not significantly increase the antibacterial efficacy against both pathogens. While washing fruit surfaces with distilled water resulted in 1.90 and 1.27 log10 CFU/mL of rinse fluid reduction of L. monocytogenes and E. coli O157:H7, respectively, > 2.60 log10 CFU/mL of rinse fluid reduction of L. monocytogenes and up to 2.35 and 3.12 log10 CFU/mL of rinse fluid reduction of E. coli O157:H7 were observed on fruit surfaces washed with EO water and NaOCl solution, respectively. Listeria monocytogenes and E. coli O157:H7 populations decreased over storage regardless of prior treatment. However, EO water and aqueous NaOCl did not show higher antimicrobial potential than water treatment during refrigeration storage.

Microbe(s): Listeria monocytogenes

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The ability of electrolyzed (EO) water to inactivate Listeria monocytogenes in suspension and biofilms on stainless steel in the presence of organic matter (sterile filtered chicken serum) was investigated. A five-strain mixture of L. monocytogenes was treated with deionized, alkaline EO, and acidic EO water containing chicken serum (0, 5, and 10 ml/liter) for 1 and 5 min. Coupons containing L. monocytogenes biofilms were also overlaid with chicken serum (0, 2.5, 5.0, and 7.5 ml/liter) and then treated with deionized water, alkaline EO water, acidic EO water, alkaline EO water followed by acidic EO water, and a sodium hypochlorite solution for 30 and 60 s. Chicken serum decreased the oxidation-reduction potential and chlorine concentration of acidic EO water but did not significantly affect its pH. In the absence of serum, acidic EO water containing chlorine at a concentration of 44 mg/liter produced a > 6-log reduction in L. monocytogenes in suspension, but its bactericidal activity decreased with increasing serum concentration. Acidic EO water and acidified sodium hypochlorite solution inactivated L. monocytogenes biofilms to similar levels, and their bactericidal effect decreased with increasing serum concentration and increased with increasing time of exposure. The sequential 30-s treatment of alkaline EO water followed by acidic EO water produced 4- to 5-log reductions in L. monocytogenes biofilms, even in the presence of organic matter.

Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes

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The effects of chlorine and pH on the bactericidal activity of electrolyzed (EO) water were examined against Escherichia coli O157:H7 and Listeria monocytogenes. The residual chlorine concentration of EO water ranged from 0.1 to 5.0 mg/l, and the pH effect was examined at pH 3.0, 5.0, and 7.0. The bactericidal activity of EO water increased with residual chlorine concentration for both pathogens, and complete inactivation was achieved at residual chlorine levels equal to or higher than 1.0 mg/l. The results showed that both pathogens are very sensitive to chlorine, and residual chlorine level of EO water should be maintained at 1.0 mg/l or higher for practical applications. For each residual chlorine level, bactericidal activity of EO water increased with decreasing pH for both pathogens. However, with sufficient residual chlorine (greater than 2 mg/l), EO water can be applied in a pH range between 2.6 (original pH of EO water) and 7.0 while still achieving complete inactivation of E. coli O157:H7 and L. monocytogenes.

Microbe(s): Escherichia coli O157: H7, Listeria monocytogenes

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Raw fish is prone to the risk of microbial outbreaks due to contamination by pathogenic microorganisms, such as Escherichia coli O157:H7 and Listeria monocytogenes. Therefore, it is essential to treat raw fish to inactivate pathogenic microorganisms. Electrolyzed Oxidizing Water (EO) is a novel antimicrobial agent containing acidic solution with a pH of 2.6, Oxidation Reduction Potential (ORP) of 1150 mV, and 70 90 ppm free chlorine, and alkaline solution with a pH of 11.4 and ORP of 795 mV. This study was undertaken to evaluate the efficacy of acidic EO water treatment and alkaline EO water treatment followed by acidic EO water treatment at various temperatures for the inactivation of E. coli O157:H7 and L. monocytogenes Scott A on the muscle and skin surfaces of inoculated salmon fillets. Inoculated salmon fillets were treated with acidic EO water at 22 and 35 C and 90 ppm free-chlorine solution as control at 22 C for 2, 4, 8, 16, 32, and 64 min. The acidic EO water treatments resulted in a reduction of L. monocytogenes Scott A population in the range of 0.40 log10 CFU/g (60%) at 22 C to 1.12 log10 CFU/g (92.3%) at 35 C. Treatment of inoculated salmon fillets with acidic EO water reduced E. coli O157:H7 populations by 0.49 log10 CFU/g (67%) at 22 C and 1.07 log10 CFU/g (91.1%) at 35 C. The maximum reduction with chlorine solution (control) was 1.46 log10 CFU/g (96.3%) for E. coli O157:H7 and 1.3 log10 CFU/g (95.3%) for L. monocytogenes Scott A at 64 min. A response surface model was developed for alkaline treatment followed by acidic EO water treatment to predict treatment times in the range of 5 30 min and temperatures in the range of 22 35 C for effective treatment with alkaline EO water followed by acidic water, alkaline and acidic water treatments. Response surface analysis demonstrated maximum log reductions of 1.33 log10 CFU/g (95.3%) for E. coli O157:H7 and 1.09 log10 CFU/g (91.9%) for L. monocytogenes Scott A. Data collected from the treatments was used to develop empirical models as a function of treatment times and temperature for prediction of population of E. coli O157:H7 and L. monocytogenes Scott A. Correlations (R2) of 0.52 and 0.77 were obtained between model predicted and experimental log10 reduction for E. coli O157:H7 and L. monocytogenes Scott A reductions, respectively. These results clearly indicated that EO water has a potential to be used for decontamination of raw fish.

Microbe(s): Listeria monocytogenes

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Biofilms are potential sources of contamination to food in processing plants, because they frequently survive sanitizer treatments during cleaning. The objective of this research was to investigate the combined use of alkaline and acidic electrolyzed (EO) water in the inactivation of Listeria monocytogenes biofilms on stainless steel surfaces. Biofilms were grown on rectangular stainless steel (type 304, no. 4 finish) coupons (2 by 5 cm) in a 1:10 dilution of tryptic soy broth that contained a five-strain mixture of L. monocytogenes for 48 h at 25 C. The coupons with biofilms were then treated with acidic EO water or alkaline EO water or with alkaline EO water followed by acidic EO water produced at 14 and 20 A for 30, 60, and 120 s. Alkaline EO water alone did not produce significant reductions in L. monocytogenes biofilms when compared with the control. Treatment with acidic EO water only for 30 to 120 s, on the other hand, reduced the viable bacterial populations in the biofilms by 4.3 to 5.2 log CFU per coupon, whereas the combined treatment of alkaline EO water followed by acidic EO water produced an additional 0.3- to 1.2-log CFU per coupon reduction. The population of L. monocytogenes reduced by treatments with acidic EO water increased significantly with increasing time of exposure. However, no significant differences occurred between treatments with EO water produced at 14 and 20 A. Results suggest that alkaline and acidic EO water can be used together to achieve a better inactivation of biofilms than when applied individually.

Microbe(s): Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus

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Aim: To ascertain the efficacy of neutral electrolysed water (NEW) in reducing Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes on glass and stainless steel surfaces. Its effectiveness for that purpose is compared with that of a sodium hypochlorite (NaClO) solution with similar pH, oxidation-reduction potential (ORP) and active chlorine content. Methods and Results: First, the bactericidal activity of NEW was evaluated over pure cultures (8-5 log CFU ml-1) of the abovementioned strains: all of them were reduced by more than 7 log CFU ml-1 within 5 min of exposure either to NEW (63 mg l-1 active chlorine) or to NaClO solution (62 mg l-1 active chlorine). Then, stainless steel and glass surfaces were inoculated with the same strains and rinsed for 1 min in either NEW, NaClO solution or deionized water (control). In the first two cases, the populations of all the strains decreased by more than 6 log CFU 50 cm-2. No significant difference (P 0 05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO solution) or to the type of surface. Conclusions: NEW was revealed to be as effective as NaClO at significantly reducing the presence of pathogenic and spoilage bacteria (in this study, E. coli, L. monocytogenes, P. aeruginosa and S. aureus) on stainless steel and glass surfaces. Significance and Impact of the Study: NEW has the advantage of being safer than NaClO and easier to handle. Hence, it represents an advantageous alternative for the disinfection of surfaces in the food industry.

Microbe(s): Listeria monocytogenes

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The effectiveness of electrolyzed oxidizing (EO) water for the inactivation of L. monocytogenes insuspension and when inoculated on lettuce leaves was evaluated. An electrolytic cell for the production of EO water was built and a solution of 5% NaCl was used. The EO water produced had a residual chlorine concentration of 29 parts per million (ppm) and pH 2.83. Ten strains of L. monocytogenes isolated from processed chicken (109 CFU/ml) were inoculated into 9 ml of EO water or 9 ml of deionized water (control) and incubated at 15 C for 5, 10, 15 and 20 min. The surviving population of each strain was determined on Columbia agar. An exposure time of 5 min reduced the populations by approximately 6.6log CFU/ml. The most resistant strains to sodium hypochlorite (NaOCl) were selected and used in a strain mixture (9.56 log CFU/ml, 109UFC/ml approximately) for the inoculation of 35 lettuce samples, by the dip inoculation method using distilled water as control. The population mean of L. monocytogenes after treatment with EO water and distilled water was reduced by 3.92 and 2.46 log CFU/ml respectively (p=0.00001). EO water and 6% acetic acid (vinegar) were combined to improve the EO water effect on L. monocytogenes inoculated in lettuce; the effectiveness of this combination was examined. The results showed that there was a synergistic effe